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Worcester Bosch Greenstar 2000 Fault Codes

Worcester Bosch Greenstar 2000 Fault Codes

Just below, is a typical list of Worcester Bosch Greenstar 2000 fault codes, which we plan to give you as much information as possible.

Please note: This is a guide for a qualified emergency boiler repair trades-person only, however, can be used by the public, to give them an idea of the trades-persons work with an idea of what to expect.

In the image, is a picture of a Worcester Bosch Greenstar 2000 using 3D art work by Meta Home and if you want to visualise the boiler in 3D, visit the about Worcester Bosch Greenstar 2000 page.


List of Worcester Bosch Greenstar 2000 fault codes

  • 200 - The Device is currently heating
  • 201 - The appliance is in DHW mode
  • 202 - The appliance is in optimised switching mode: the interval for restarting the burner has not yet expired (service function 3-b2)
  • 203 - The appliance is on standby, there is no heat demand
  • 204 - The current flow temperature is higher than the set flow temperature. The burner has been switched off
  • 207 - Operating pressure too low
  • 208 - The appliance is in chimney sweep mode. Chimney sweep mode is deactivated automatically after 30 minutes
  • 212 - Temperature increase for safety or flow temperature sensor too fast
  • 214 - The fan stops during the safety time
  • 215 - Fan too fast
  • 224 - Flue gas temperature limiter or heat exchanger temperature limiter has tripped
  • 227 - No flame detected
  • 228 - Flame signal is present although burner is switched off
  • 229 - Flame lost during burner operation
  • 232 - Heat source locked by external switching contact
  • 233 - Fault in code plug or appliance electronics
  • 234 - Electrical fault in gas valve
  • 235 - Version conflict between appliance electronics and code plug
  • 237 - System fault
  • 238 - appliance electronics faulty
  • 242 - System fault, appliance electronics
  • 244 - System fault, appliance electronics / basic controller
  • 246, 247, 257 - System fault, appliance electronics
  • 245, 249, 250, 251, 252, 253 and 254 - System fault, appliance electronics / basic controller
  • 256 - System fault, appliance electronics / basic controller
  • 258 - Internal fault in control unit
  • 259, 262 and 263 - System fault, appliance electronics
  • 264 - Air feed failed during operating phase
  • 265 - Heat energy demand lower than energy supplied.
  • 268 - Component test mode
  • 269 - Flame monitoring
  • 270 - The heat source has started up
  • 273 - Operation interrupted: safety inspection following 24 hours of continuous operation
  • 275 - Test code plug detected
  • 281 - Pump stuck or running dry
  • 305 - Boiler cannot start temporarily following DHW priority
  • 306 - After switching gas off: Flame is detected
  • 323 - Control communication fault
  • 328 - Mains voltage briefly interrupted
  • 341 - Heat source temperature increase too rapid
  • 342 - Temperature increase in DHW mode too rapid
  • 350 - Flow temperature sensor short circuit
  • 351 - Flow temperature sensor failure
  • 356 - Supply voltage for heat source too low
  • 357 - Venting program
  • 358 - Active anti-seizing function
  • 360 - Incorrect code plug
  • 362 - Service code plug detected
  • 363 - System fault, appliance electronics: fault when testing the ionisation signal
  • 364 - Solenoid valve EV2 leakingSolenoid valve EV2 leaking
  • 365 - Solenoid valve EV1 leaking
  • 604 - System fault, burner control unit
  • 810 - DHW temperature has not increased for 2 hours
  • 815 - Faulty low loss header temperature sensor
  • 1013 - Maximum combustion point reached
  • 1014 - Ionisation current is too low
  • 1017 - Water pressure too low
  • 1018 - Service time expired
  • 1021 - DHW temperature sensor faulty
  • 1022 - DHW temperature sensor is faulty
  • 1023 - Maximum operation time including standby is reached
  • 1065 - Pressure sensor faulty or not connected
  • 1068 - Outside temperature sensor faulty
  • 1073 - low temperature sensor short circuit
  • 1074 - No signal from the flow temperature sensor
  • 1075 - Short circuit in heat exchanger temperature limiter
  • 1076 - No signal from heat exchanger temperature limiter
  • 2051 - Internal fault
  • 2085 and 2908 - Internal fault in burner control unit
  • 2909 - System fault, appliance electronics / basic controller
  • 2910 - Fault in flue system
  • 2911 - Calibration failed
  • 2912 - No flame signal during calibration
  • 2913 - Flame signal too low during calibration
  • 2914 - System fault, appliance electronics
  • 2915 - System fault, appliance electronics
  • 2916 - System fault, appliance electronics
  • 2917 - No flame signal when checking the combustion control
  • 2918 - Fault in the flue
  • 2920 - Flame monitoring fault
  • 2921 - The appliance is in test mode
  • 2922 - System fault, appliance electronics
  • 2923 and 2924 - System fault, appliance electronics
  • 2925 and 2926 - System fault, appliance electronics
  • 2927 - No flame detected during ignition
  • 2932 - Internal fault
  • 2928, 2930, 2931 and 2940 - Internal fault in burner control unit
  • 2941 - Insufficient flow rate in heat source
  • 2942 - No fan speed feedback
  • 2943 - Mains voltage too low
  • 2945 - Too many short heat demands in a short time
  • 2946 - Incorrect code plug
  • 2947 - Anti-seizing function is activated
  • 2948 - No flame signal with low output
  • 2949 - No flame signal with high output
  • 2950 - No flame signal following starting procedure
  • 2951 - Loss of flame too frequent
  • 2952 - Internal fault when testing the ionisation signal
  • 2953 - No flame signal with low output
  • 2954 - No flame signal with high output
  • 2955 - The heat source does not support the specified parameters for the hydraulic configuration
  • 2956 - Hydraulic configuration at the heat source is activated
  • 2957 and 2958 - System fault, appliance electronics
  • 2959 and 2960 - System fault, appliance electronics
  • 2961 and 2962 - No signal from fan
  • 2963 - The signal from the heat exchanger temperature limiter and flow temperature sensor is outside the permissible range
  • 2964 - Insufficient flow rate in heat exchanger
  • 2965 - Flow temperature too high
  • 2966 - Flow temperature increase in heat exchanger too rapid
  • 2967 - Temperature differential between flow temperature sensor and heat exchanger temperature limiter is too great
  • 2968 - Refilling of system in progress
  • 2969 - Maximum number of refills reached
  • 2971 - Operating pressure too low
  • 2972 - Mains voltage too low
  • 2973 - System fault, appliance electronics / basic controller
  • 2974 - Internal error
  • Green continuous - Normal operation
  • Green/Red blinking - Warning mode (pump operating in an abnormal condition, no risk for the pump functionality)
  • Red blinking - Abnormal running mode (pump stopped but still functioning)
  • Red continuous - Pump stopped
  • No LED - No power supply
  • Combustion noises too loud
  • Flow noises
  • Heat-up taking too long
  • Flue gas values incorrect
  • Delayed ignotion, poor ignition
  • Condensate in air box
  • No hot water
  • DHW volumn is not reached
  • No function, the diplay remains dark

207 - Operating pressure too low

The 207 error code is related to low water pressure and the remedy to repair this issue can be easilly dealt with by filling the water pressure up, however, this doesn't rule out having to replace the pressure sensor.

212 - Temperature increase for safety or flow temperature sensor too fast

The 212 error code is related to the open shut off valves.

214 - The fan stops during the safety time

In regards tot eh error code 214, this is a fan fault, that requires a voltage check, meaning there is also a good chace the fan needing to be replaced.

215 - Fan too fast

The 215 error code relates to the fan being too fast that could be an issue with the PCB, the voltage default value corresponding with the fan may require checking. It is best to check the PCB & the harness, then replace if necessary.

224 - Flue gas temperature limiter or heat exchanger temperature limiter has tripped

If the blocking fault persists for a prolonged period, it becomes a locking fault. It is likely the following will need to be checked & replace if required:

  • Position of isolation valve in heating circuit, open if required
  • Water pressure, if necessary top up until the preset pressure is reached
  • The temperature limiter and connecting lead of the heat exchanger for breaks
  • Flue gas temperature limiter and the connecting lead for breaks
  • Vent appliance with service function 4-A1

227 - No flame detected

If the error code 227 comes up, this is likely due to no flame being detected, it would then be expected that after the 5th ignition attempt, the blocking fault then becomes a locking fault. It is likely the following checks will need to be made following a replacement if required:

  • Gas isolator is open
  • Gas supply pressure
  • Ionisation signal
  • Power supply
  • Electrodes with cable
  • Flue system, clean
  • gas/air ratio, adjust if required
  • Clean heat exchanger
  • Gas valve
  • Burner setting, correct if necessary

228 - Flame signal is present although burner is switched off

The error code 228 relates to the flame signal being present, even thought the burner is switches off, however, it may be worth checking the flame is present. The following checks can also be made, then replace if necessary:

  • Electrodes and connecting leads
  • Gas valve
  • Appliance electronics

229 - Flame lost during burner operation

If the flame is lost during the operation giving you the error code 229, the following checks should be made and replace if necessary:

  • Main shut-off valve
  • Appliance isolation valve
  • Measure the gas supply pressure at the rated heat input. If necessary, shut down the appliance and check the gas line
  • Flame sense electrode and connecting lead
  • Venturi/injector for potential blockage
  • Measure the ionisation current
  • Protective conductor connection in the control unit
  • Ignition cable for damage
  • Functionality of gas valve
  • Burner setting value at rated heat input
  • Burner setting value at the lowest output
  • Flue system
  • Combustion air supply
  • Heat exchanger on the flue gas side for deposits, clean if necessary

232 - Heat source locked by external switching contact

If you get a 232 error code due to the heat source being locked by the external switching contact, it is worth trying to connect this first, then check the following:

  • Install jumper/check condensate pump according to manufacturer's specifications
  • Adapt switching point of the external temperature switch to the system
  • Replace connecting lead to the external temperature switch
  • Replace external temperature switch

233 - Fault in code plug or appliance electronics

If you're having an issue with a fault in the code plug, or the appliance electronics due to a 233 error code, it is worth checking if the code plug is installed correctly and you can check the appliance electronics.

234 - Electrical fault in gas valve

If the gas valve get an electronic fault giving you a 234 error code, this could be related to the connecting lead or/and the gas valve may need replacing.

235 - Version conflict between appliance electronics and code plug

The 235 is a problem due to the conflict between the appliance electronics and code plug, which requires the softwear version of applicance electronics and code plugs checking, this may require the appliance electronics or code plug replacing.

237 - System fault

If you have a system fault due to a 237 error code, it is best that code plug is checked and replaced.

238 - appliance electronics faulty

If your appliance electronics becomes faulty, this is likely going to bring up a 238 error code, this means it repair this, it is likely you will need to have the appliance electonics replaced.

242 - System fault, appliance electronics

If you're getting a 242 error code, then if may be best giving it a factory reset by resetting the control appliance/burner control unit. Reconnect electrical connections at control unit/ burner control unit correctly. You many need to replace the control unit/burner control unit if required.

244 - System fault, appliance electronics / basic controller

If you're getting a 244 error code, then if may be best giving it a factory reset by resetting the control unit/burner control unit. Reconnect electrical connections at control unit/ burner control unit correctly. You many need to replace the control unit/burner control unit if required.

246, 247, 257 - System fault, appliance electronics

If you're getting either one of the following codes being 246, 247 or 257, then this is relating to the internal burner control fault, which you will need to reset, then factory reset. The electrical connections of burner control may need checking and possible replacing.

245, 249, 250, 251, 252, 253 and 254 - System fault, appliance electronics / basic controller

If you're getting either one of the following codes being 245, 249, 250, 251, 252, 253 or 254, then this is relating to the System fault, appliance electronics, which you will need to reset appliance electronics. The electrical connections of appliance electronics may need checking and possible replacing.

256 - System fault, appliance electronics / basic controller

If you're getting a 256 error code, then if may be best giving it a factory reset by resetting the control unit/burner control unit. Reconnect electrical connections at control unit/ burner control unit correctly. You many need to replace the control unit/burner control unit if required.

258 - Internal fault in control unit

The error code is an internal fault in the control unit, which you should try to reset - factory reset. make sure the electrical connections are connected correctly. You may need to replace the control unit.

259, 262 and 263 - System fault, appliance electronics

If you get any of the codes 259, 262 or 263, this means their's a system fault to teh appliance electronics, which you can reset - factory reset. You can check electrical connection and replace if required.

264 - Air feed failed during operating phase

First of all, when it comes to an error code 264, you will need to check the fan plug, that it's connect properly by taking it out, and placing it back in, then performing a reset.

If resetting fails, replace the fan and the mains voltage must correspond to the deault value. Remove any blockages in the flue system and check any venturi/injector for any pottential blockage.

268 - Component test mode

This is just a test mode and no remdey is required.

269 - Flame monitoring

The error code 269 is flame monitoring, which means you will need to try and reset the appliance electronics, possibly to factory settings. If this is not succesful, it is best to replace them.

Before replacing the appliance electronics, it may be worth noting that the connections may need disconnecting and reconnecting, making sure they are also kept securely intact, making sure that the earth is also intact.

281 - Pump stuck or running dry

If the pump is running dry or is stuck, it is likely you will get a 281 error code and if this is the case, firstly, check the pump connections, check the low pressure switch and operating pressure and vent the system.

If the issue with the error code persists, then replace the pump and follow the process again.

305 - Boiler cannot start temporarily following DHW priority

This error code belongs to the system appliance only.

306 - After switching gas off: Flame is detected

The 306 error code relates to the gas valve or the electrodes and connection leads, which either of these may need replacing. It is also possible that the appliance electronics will need replacing.

Before replacing hte above items, it is best to disconnect and reconnect the wiring securely.

328 - Mains voltage briefly interrupted

The 328 error code general happens when the mains voltage is briefly interupted, and the best thing to do is to check the voltage interuption between the electrical wiring system of the building and the appliance.

341 - Heat source temperature increase too rapid

If you find the heat source temperature increasing too rapidly giving you an error code of 341, firstly, check isolation valves are open and if not, then open them.

You may want to check the pump is plugged in and if the pump is faulty, then replace the pump.

You can also check the pump by putting it on a constant flow. setting 3 seen as | - || - |||.

342 - Temperature increase in DHW mode too rapid

The 342 error code means that the DHW, known as the domestic hot water, is the temperature mode too rapid. This could be easily solved by the occupier of the home by simply pressuring the water to the correct operating pressure.

If the issue becomes a little more technical, it is wise to open the service valve on the cylinder charging unit and if the issue persists, you may need to have the diverter valve or/and cylinder pump replaced.

350 - Flow temperature sensor short circuit

The 350 error code related to the flow temperature sensor short circuit, so the first thing to do is to replacement the sensor the harness.

If the issue isn't fixedm replaced the leads or/and replace the control unit/burner control unit.

351 - Flow temperature sensor failure

The 351 error code related to the flow temperature sensor failing, so the first thing to check would be the cable connections, disconnecting and reconnecting, following a replacement including the harness.

You may need to replace the lead to the flow sensor, or as a job lot, it may be wise to replace them together and if this fails, check and replace the control unit/burner control unit.

356 - Supply voltage for heat source too low

If the supply voltage for the heat source is too low, this could bring up an error code being 356 and the remedy for this is to establish the supply voltage being at least 196 VAC (Volts Alternative Current).

357 - Venting program

The code 357 just explained that the boiler is just venting the program, which shouldn't be a worry, unless an alterntive fault code came up requiring further attention.

358 - Active anti-seizing function

The error code 358 is the active anti-seizing fuction and the remedy for this is blocking protection for the heating pump and diverter valve active.

360 - Incorrect code plug

The incorrect code plug will bring up the code 360, so the best thing to do here would be to check the code plug and replace if necessary.

362 - Service code plug detected

The error code 362 is very similar to the error code 360, however, the only diverence is that it revers to 'service code plug detected', however, the remedy is the same.

363 - System fault, appliance electronics: fault when testing the ionisation signal

When your testing the ionisation signal and your getting a system fault on the appliance electronics, you will need to check the earthing connections, then reset the appliance electronics or replace if necessary.

364 or/and 365 - Solenoid valve EV2 or EV1 leaking

If the solenoid valve EV2 or EV1 is leaking, it will bring up the error code either being 364 or 365.

The error code 365 relates to the error code EV1 and the error code 364 related to EV2. These codes code can be easy to get mixed up because the lower number can related to the high number on the valve.

The remedy for the error codes EV1 or EV2 is to check the gas valve, check electrodes and connections, replace either of these or/and replace the appliance electronics.

604 - System fault, burner control unit

Is your boiler is bringing up an error code of 604 and your wandering what that is, it's to do with a system fault, burner control unit.

The remedy for this is to reset the appliance, to manufacty reset and if the fault persists, the burner control unit is faulty and must be replaced.

810 - DHW temperature has not increased for 2 hours

If your domestic hot water temperature has not increased for 2 hours, this can bring up an 810 error code on your boiler. As a remedy, there are many things you could look into following the list below:

  • Prevent water from escaping.
  • Position DHW temperature sensor correctly.
  • If no voltage can be measured, then the MC10 control panel is faulty and must be replaced.
  • If power is being supplied to the DHW cylinder charge pump but it is still not running, it is faulty and must be replaced.
  • If power cannot be supplied to the DHW cylinder charge pump, then there is a problem in the cable between the control panel and pump. Check screw terminals and cables.
  • If current is not being supplied to the 3-way valve, there is a problem in the cable between the control panel and valve. Check screw terminals and cables.
  • If current is being supplied to the 3-way valve but it is still not working, the valve is faulty and must be replaced.
  • If a voltage of approx. 230 V is measured at the terminals and the pump is not running, the pump is faulty and must be replaced.
  • Eliminate all faults in the cables. Vent if necessary.
  • Replace the pump if there are any deviations whatsoever.
  • Set the DHW heating to “Priority”.
  • If readings are different to the values in the table, replace the sensor.

815 - Faulty low loss header temperature sensor

The error code 815 relates to the faulty low loss header temperature sensor. To resolve this, you will need to check out the sensor port and/or check the temporature for incorrect installation position or breakage.

1013 - Maximum combustion point reached

The error code 1013 means that the maximum combustion point has been reached, which you will need to check the plausibility of displayed cylinder temperature, the plug-in connectors and cable harness for contact and replace cylinder temperature sensor i frequired.

1014 - Ionisation current is too low

If the Ionisation current is too low, the error code 1014, there is no remedy for this.

1017 - Water pressure too low

The erro code 1017 relates to the water pressure being to low, so the best thing to do is check the water pressure is low, and if necessary, top the water pressure up or check the pressure sensor and replace if required.

1018 - Service time expired

If you're getting an error code 1018, this means that your service time has expired, meaning you should make contact with a heating engineer, either a local engineer or contact a nation company that could assist you.

1021 - DHW temperature sensor faulty

Got a 1021 error code, this related to the DHW meaning domestic hot water temperature sensor being faulty. Checking the plug connections is conected property is likely the first thing to try. Checking the position of the temperature sensor is correctly positioned and if not, reposition.

Check the temperature sensor using an electronic tool and replace if neccesary. You can also check the connections being correctly fitted for breaks or shortcuts and replace if needed.

I fthe issue is not resolved, replace the appliance electronics.

1022 - DHW temperature sensor is faulty

The 1022 means the DHW temperature sensor is faulty.

1023 - Maximum operation time including standby is reached

You will need to perform an inspection if the maximum operation time including standby is reached resulting in the error code 1023.

1065 - Pressure sensor faulty or not connected

The error code 1065 means that either the pressure sensor is faulty or just not connected, you can check this by checking the plugs and the pressure sensor, then replace if necessary.

You can also check connecting lead for breaks or short circuits and replace if required and if this does not resolve the issue, it is best to check the appliance electronics and replace.

1068 - Outside temperature sensor faulty

The 1068 error code means that the outside temperature sensor is faulty and could be a contact problem or the sensor will need replacing.

1073 - low temperature sensor short circuit

If you're getting a flow temperature short circuit, this will tend to bring up the error code 1073 and the remedy to resolve this could related to either the temperature sensor, the connection leads for short cuts or the appliance connections, either of them needed to replace if necessary.

1074 - No signal from the flow temperature sensor

If you're getting no signal from the flow temperature sensor bring up the error code 1074, it is best to check the plug is connecting correctly, check flow temperature sensor, connecting lead for breaks or the appliance electronics and replace either if necessary.

1075 - Short circuit in heat exchanger temperature limiter

A short circuit in heat exchanger temperature limiter can bring up a 1075 error code, this means you will need to check the heat exchanger temperature limiter, the connecting lead for short circuits, the appliance electronics and replace either if necessary.

1076 - No signal from heat exchanger temperature limiter

If your getting no signal from the heat exchanger temperature limiter, it will tend to bring up an error code of 1076. This could be due to lose connections or the heat exchanger temperature limiter itself, which can be checked, sometimes it could be a breakage in the lead itself or you may need to replace the appliance electronics.

2051 - Internal fault

The error code 2051 is an internal fault, this means you will need to disconnect the power from the system for 30 seconds, this may also mean that the control unit will need replacing.

If required, you will need to notify customer service.

2085 and 2908 - Internal fault in burner control unit

If you get a 2085 or a 2908 error code, these codes relate to a fault internally on the burner control unit, firstly, it is best to reset the appliance, then if the fault persists, the burner control unit is faulty and must be replaced.

2909 - System fault, appliance electronics / basic controller

When you get a system fault relating to the appliance electronics basic controller, an error code 2909 will appear, and the remedy to try and resolve this could be to just reset or the burner control unit including in interconnecting leads must be faulty and must be replaced.

2910 - Fault in flue system

If a fault occures in the flue system, this should bring up the error code 2910, firstly you could check the flue system and install if required, or/and check for unobstructed cross-section of flue system, remove deposits if required.

2911 - Calibration failed

The 2911 error code is due to a calibration failure, which required the faulty component to be replaced.

2912 - No flame signal during calibration

The 2912 error code is due to a flame not signalling, which required the faulty component to be replaced.

2913 - Flame signal too low during calibration

If the flame signal is too low, this will bring up the 2913 error code, which will require a check and a repalcement for the flame sense electronics and interconnecting leads.

2914, 2915 or 2916 - System fault, appliance electronics

The error codes 2914, 2915 and 2915, can all be related to the system fault, appliance electronics that could be broken up between 3 categories for there remedies.

  • The error code 2914 means if the fault persists following a reset of the boiler, the appliance control unit is faulty and should be replaced.
  • The error code 2915 means to reset the boiler and if the fault persists following a reset, the control unit is faulty and must be replaced.
  • If you get the error code 2916, firstly try to reset the appliance, trigger heat demand, end heat demand and if the fault persists, replace the control unit.

2917 - No flame signal when checking the combustion control

When checking the combustion control and you get an error code 2017 which is the flame signal, firstly, disconnect the power and reconnect, trigger heat demand and wait for 5 minutes.

If the fault happens again within that time reset the appliance without disconnecting the supply voltage. This should trigger a calibration of the ionisation circuits, however, if the fault is still there, the control unit is faulty and should be replaced.

2918 - Fault in the flue

If a fault occures in the flue, this will tend to bring in the error code 2918 up on the display, for this to be resolved, it is best to clean the sysphon, and drain out the appliance, whis could be done as part of a service.

2920 - Flame monitoring fault

The error code 2920 related to the flame monitoring circuit being faulty, firstly check all connections and replace if required, check earthing and appliance electronics, then replace if required.

2922 - System fault, appliance electronics

The error code 2920 is an internal burner control fault, which you will need to check and replace if required.

2923, 2924, 2925 or 2926 - System fault, appliance electronics

If you get either the 2923, 2924, 2925 or the 2926 error code, all these codes relate to the system beign faulty on the appliance electronics. These error codes can be broken up into catorgories of appliance electronic faults

With the 2923 or the 2924 error code, reset the applaince and if the fault persist following the reset the appliance electronics are faulty and should be replaced.

With the 2925 or the 2926 error code, check the gas valve or/and the appliance electronics, then replace either parts if required.

2927 - No flame detected during ignition

If you're wondering why your boiler isn't firing up and you're getting an erro code of 2927, there can be many reasons for this to happen. Just below is a list of things to check:

  • Main shut-off valve, open if necessary
  • Appliance isolation valve, open if necessary
  • Measure the gas supply pressure at the rated heat input. If necessary, shut down the appliance and check the gas line
  • Flame sense electrode and connecting lead, replace if required
  • Check venturi/injector for potential blockage
  • Measure the ionisation current
  • Protective conductor connection in the control unit
  • Ignition cable for damage, replace if necessary
  • Functionality of gas valve and replace if necessary
  • Burner setting value at rated heat input
  • Burner setting value at the lowest output

2932 - Internal fault

The error code 2932 is an internal fault where you would need to replace the appliance.

2928, 2930, 2931 and 2940 - Internal fault in burner control unit

If you're getting either the following faults being 2928, 2930, 2931 and 2940, this means there is an internal fault in burner control unit, to remedy this, reset teh appliance to factory settings and if the fault persists following the reset, the burner control is fault and should be replaced.

2941 - Insufficient flow rate in heat source

If you're getting an insufficient flow rate in the heat source, this should bring up the error code 2941, and to try and resolve this, you should check the following:

  • Plug of flow temperature sensor
  • Flow temperature sensor
  • Pump for blockage, clear if required
  • Pump settings, correct if required
  • Water pressure, if necessary top up until the preset pressure is reached

If the issue is with the flow temperature sensor or the plug to the flow sensor, replace them if required.

2942 - No fan speed feedback

If you have no fan speed, the error code 2942 should show up, to remedy this, try connecting the plug for the speed control to the fan, followed by the plug for the power supply to the fan.

Next you will need to check the harness and maybe check and replace the control unit.

2943 - Mains voltage too low

If the main voltage is too low and you're getting the arror code 2943 coming up, you will need to establish the supply voltage to be at least 196 VAC.

2945 - Too many short heat demands in a short time

If you're getting too many heat demans in a short time, the error code 2945 should show, first of all, try setting the appliance to factory reset, increase restart blocking time making sure at least one thermostat valve is open. You can also check and replace the following if necessary

  • Heating pump
  • Diverter valve
  • Code plug

2946 - Incorrect code plug

If the code plug is incorrect, this should bring up the error code 9246, meaning the plug should be replaced.

2947 - Anti-seizing function is activated

If the anti-seizing function activates, this should trigger that error code 2947 where the remedy is that the function stops automatically.

2948 - No flame signal with low output

If you're getting no flame signal with low output, this should bring up the error code 2948, and to remedy this, that the burner restarts automatically after purging, check the CO2 settings.

2949 - No flame signal with high output

If you're getting no flame signal with high output, this should bring up the error code 2948, and to remedy this, that the burner restarts automatically after purging, check burner gasket and replace if required, then check the CO2 settings.

2950 - No flame signal following starting procedure

The error code 2950 means no flame signal following starting procedure. Firstly checl teh CO2 settings and adjust if required, check burner and heat exchanger gaskets, check gas pressure during burning at full load, then burner restarts automatically after purging.

2951 - Loss of flame too frequent

If the loss of flame is too frequent, this should cause the boiler to show an error code 2951, this means you will first need to refer to the blocking error or errors that lead to teh locking error, then check the fault history on the appliance.

You may need to purge the gas pipe as this may be incomplete, keeping in mind that could also indicate a wide variety of issues such as pipework undersized or gas pressure dropping off, incorrectly routed condense drains, incorrectly sited flues, incorrectly wired and so on.

2952 - Internal fault when testing the ionisation signal

If you get a 2952 fault error code, this is related to the internal fault when testing the ionisation signal, which you are best restarting the appliance to see if it re-occures.

If the fault remains after resetting, the burner controller (PCB) is defective.

2953 - No flame signal with low output

If you're getting low flame sign, and low output, this will tend to bring up the error code 2953. The burner starts automatically after cleaning (purge), possibly caused by high winds.

If the fault occurs repeatedly, check the settigns of the CO2 values, the flue integrity and terminal.

2954 - No flame signal with high output

If you're getting low flame sign, and high output, this will tend to bring up the error code 2954. Burner restarts automatically after purging. Here is a list of what you need to check:

  • Check and replace burner gaskets
  • Reduce burner load
  • If the fault occurs repeatedly, check the settings of the CO2 values
  • Check Flue integrity & Flue terminal

2955 - The heat source does not support the specified parameters for the hydraulic configuration

If the heat source does not support the specified parameters for the hydraulic configuration, you should check the hydraulic configuration and correct if necessary. You can also check the menu L2 and default setting to 0 if required.

2957, 2958, 2959 and 2960 - System fault, appliance electronics

If you're getting either of the codes 2957, 2958, 2959 or 2960, all these codes relate to a system fault on the appliance electronics.

In regards to the first 2 fault codes being 2957 and 2958, the remedy for these are to reset the appliance, check electrical connections and/or replace the control unit.

In regards to the 2959 error code, you will need to check and place the control unit and code plug.

2961 and 2962 - No signal from fan

If your getting no signal from the fan, this can bring up the error code either being 2961 or/and 2962. With these codes, you should reset the appliance electronics, check electrical connections and replace control unit if required.

2963 - The signal from the heat exchanger temperature limiter and flow temperature sensor is outside the permissible range

The error code 2963 is relating to the signal from the heat exchanger temperature limiter and flow temperature sensor is outside the permissible range, first thing you should do is to check the flow through the appliance and check the system is filled.

Check for airlocks and purge, check the heat exchanger sensor (primary thermistor) and plug connected to stat following the resistance of stat and the continuity of haness, then replace if requried.

2964 - Insufficient flow rate in heat exchanger

If you're getting an insufficient flow rate in the heat exchanger, this will tend to bring up the error code 2964. Here is a list of options to check:

  • Supply sensor is not assembled on the supply pipe.
  • Supply sensor doesn't make proper contact with the supply pipe.
  • System isn't filled with water.
  • No water flow, because central heating system is closed.
  • No water flow, because the central heating pump is not operating correctly.

2965 - Flow temperature too high

When the flow temperature is too high, this will tend to bring up the error code 2965, which the flow through the appliance and system pressure will need checking.

You can also check for airlocks and purge if needed followed by checking the isolation valves.

2966 - Flow temperature increase in heat exchanger too rapid

If the flow temperature increases in the heat exchanger heating too raid, this should bring up the error code 2966, which firstly you should check the flow through the appliance and check the system pressure.

After checking the system pressure, check for any airlocks in the system and purge if required. Check Isolation valves and pump is operating freely, then check the voltage to the pump is ok.

2967 - Temperature differential between flow temperature sensor and heat exchanger temperature limiter is too great

If the temperature differential between the heating exchanger limiter and the temperature sensor is too great, this should bring up the error code 2967.

firstly, you should check the flow through the appliance and the system is filled, followed by any airlocked in the system and purge if required.

You can check isloation valved and pump for operation, tehn the voltage to the pump.

Another posibilty for the error code could lie with the heat exchanger sensor, and the flow sensor, making connection with the pipe work. You can check the heat exchanger and resistance of the stat, tehn replace if require followed by the continuity of the harness, then replace if required.

2971 - Operating pressure too low

When the operating pressure is too low, this will bring up the error code 2971. You can vent the system, check water pressure and fill up or replace the pressure sensor if this is the issue.

2972 - Mains voltage too low

An error code of 2972 means the mains voltage is too low, which you should check the mains voltage on the appliance live and neutral connections.

2973 - System fault, appliance electronics / basic controller

If you get an error code being 2973, this is related to a system fault on the appliance electronics basic controller, which you should perform a reset to factory settings and/or check and replace the control unit.

2974 - Internal error

With an internal error, this should bring up the error code 2974, which you should restart the appliance, tehn check if the fault remains, the you can check and place the control unit.

Green continues - Normal Operation

If you're getting a green continues light showing on your boiler, there is nothing to worry about this as it's just in a normal working mode where the pump also runs as expected.

Green/Red blinking - Warning mode (pump operating in an abnormal condition, no risk for the pump functionality)

If you're wondering if the green and red blinking is a boiler problem on the heating unit, then the answer is yes, however, it may not be that bad as we explain further.

The green and red blinking light on the Worcester bosch greenstar 2000 is a warning mode, where there is no risk to the central heating pumps functionality but is running in an obnormal condition.

The pump could be running in dry, overloading, due to debris or other reasons similar or the pump rotor is being driven by an external flow:

  • If the pump is running dry, this could just be filled up by pressurising the system, as long as there is no other heating problems such as leaks
  • If the central heating pump is overloading, this means that the pump is havign to work harder than normal, with the most likely cause being debris
  • If the pump general operation being driven by an external flow, the pump will operate normally when the external flow will be stopped

Red blinking - Abnormal running mode (pump stopped but still functioning)

The red blinking light on the Worcester bosch greenstar 2000 means that the boiler is running in an abnormal state and the pump has stopped due to an external problem. Once the external issue has been resolved, the pump should restart again.

Here is a list of things to check:

  • Under or Over voltage: Mains supply voltage U <160V or U> 280V
  • Overload of motor: Friction due to particles and/or impeller blocked with debris and/or too high viscosity.
  • Over speed: The pump rotor is driven by an external flow above the maximum allowed value.
  • Over current: Abnormal current exceeding the limit.
  • Module over temperature: Temperature inside the motor is too high.
  • Turbine mode: The pump is driven by external flow (>1200l/h) in opposite direction of its flow.

If you're getting an under or over voltage, you would be best checking the mains voltage supply to the pump being: 160V < U < 280V.

If the pump is overloading, you'll be best to check the water quality, possibly resulting in getting a system clean.

If you're getting an over speed, you will need to ensure that there is no other external flow (additional secondary pump running) on the system.

If you're getting an over current, check for any leaks on the appliance.

If the temperature on the motor is too high, check for any evidence of dry water, like due to low pressure.

With regards to the turbine, ensure that the external flow is less than 1200l/h.

Red continuous - Pump stopped

If the red solid light on the Worcester bosch greenstar is on, this would mean the central heating pump has stopped due to permanent failure. This may be due to faulty wiring or motor, it may be worth restarting the appliance and waiting 30 seconds before starting up again to see if this resolves the problem or/and replace the central heating pump, which should stop the solid red light.

No LED - No power supply

If you're not getting any power supply with no LED to show, this will mean that the pump won't be connected to the mains or you have a faulty electronics or LED. Firstly, check the power supply to the pump, if you're getting no LED, check the pump is running or replace the pump if it's the electronics.

Combustion noises too loud -

If your boiler is too loud, making you very concerned, many people seem to think the boiler will explode, however, we have no evidence of this ever happening, so here is a list of things to check:

  • Gas Type
  • Gas Supply Pressure
  • Flue System - (Clean or Repair if required)
  • Gas to air ratio
  • Ratio control valve - (Repalce if required)
  • Condense Drain being clear
  • Fan Depression

Flow noises

If your getting flow noises on the Worcester Bosch Greenstar, set the pump rate or pump characteristic map correctly and match to the maximum output.

Heat-up taking too long

If the heat up is taking too long, set the pump rate or pump characteristic map correctly and match to the maximum output and/or the system being balanced, or anti-cycle time.

Flue gas values incorrect

If the flue gas values arn't correct, being the CO content being too high, you can check the gas type, the gas supply pressure, the flue (clean and repair if needed), gas to air ratio and the ratio control valve, tehn replace if required.

Delayed ignotion, poor ignition

If you're getting a poor or delayed ignition, you can check for the following:

  • Ignition transformer function for misfiring
  • Gas type
  • Gas supply pressure
  • OperaPower supply
  • Electrodes
  • Flue system
  • Gas to air ration
  • Burner
  • Turbine

If you're finding any faults with these that cant be rectified, then replace the parts.

Condensate in air box

If you find any condensation in the air box, check the non-return valve in the air/gas manifold, then replace if needed.

No hot water

If you're gettign no hot water, check the turbine, then replace if required. You can also check for cross piping and the diverter valve.

DHW volumn is not reached

If the domestic hot water (DHW) volumn is not being reached, you can check the plate heat exchager, the flow device and the silencer body.

No function, the diplay remains dark

If you're getting no funtions and the display is remaining dark, check the electrical wiring for any damage, or the fuse may have gone, then replace either the fuse or the wiring if required.