Worcester Boiler Fault Problems And Cures


The Worcester boiler fault problems and cures Q & A or require an engineer for an emergency boiler repair.


The Worcester Boiler Fault Problems And Cures Common Q & A


Just below, we have a list of common questions relating to the Worcester Bosch Boiler.

Worcester Boiler Fault Problem And Cures

Below we’ve created an extensive guide to Worcester boiler problems, and the potential cures.

All modern boilers have a lock out function built into the appliance. When the boiler recognises a fault, it will lock out and then display a relevant fault code.

These fault codes are designed to help an emergency boiler repair engineer diagnose the problem with your boiler.

Without these fault codes, they’d be aimlessly fault finding, which would end up taking them much longer than they should and costing you much more than it should.

These fault codes are specific to a boiler brand. For Worcester boilers, you’ll notice codes such as EA 338, D1 and C6.

So, if your boiler has locked out and is displayed a fault code, you can click through to that specific fault code below.

This will give you an idea of what problem is causing the fault code to be displayed and the possible cure.

What does the A1 281 fault code mean on my Worcester Bosch boiler?


The A1 281 fault code on Worcester boilers relates to a problem with the pump. The pump is either stuck, or it’s running with air in the system.

If the pump is stuck, it’s likely that the shaft or bearings have worn out due to old age. When this is the case, you’ll need to call a boiler repair engineer to come and replace the shaft and bearings.

However, the more probable cause of the A1 281 fault code being displayed, is air trapped in the heating system. This can be bled via radiators and towel rails, and the pump itself by a Gas Safe engineer.

The next thing to check is that the boiler isn’t running dry.

Your boiler needs to be pressurised to around 1.3 bar. The more pressure there is in your boiler, the more water there is too (adding water increases the pressure). So, check that the system has 1.3 bar of pressure.

If the boiler has been topped up with water (and therefore, pressure) before but it’s dropping, there is a leak in the heating system.

An emergency boiler repair engineer will be able to locate the leak, fix it, top up the boiler’s pressure and reset the boiler to clear the A1 281 fault code.

If the B7 257 fault code is being displayed on my Worcester boiler, what does it mean?


If your Worcester Bosch boiler is showing the B7 257 fault code, the problem lies with the printed circuit board (PCB).

The PCB is the unit that controls all electrical components in your boiler. It tells the gas valve to open to provide gas to the burner, the pump to start pumping water and even gets feedback from sensors to ensure the boiler is working safely.

So, when there’s a problem with the PCB, the boiler will malfunction. This could lead to heating coming on and off randomly, or radiators/water not getting up to temperature.

The PCB is one of the most expensive parts in your boiler, and a replacement could be as much as £500. The exact price will depend on the specific model of boiler that you have.

The first point of call is to speak to an emergency electrician and heating engineer. They’ll run some quick tests on the PCB using a multi-meter. This will enable them to be 100% sure that the PCB is at fault before replacing it.

And, if it is the PCB that’s causing the B7 257 fault code to be displayed, you’ll want them to check other important components in your boiler (such as the gas valve, pump and heat exchanger).

If your boiler is particularly old and other expensive parts are likely to need replacing soon, a replacement boiler would be the most cost-effective solution, long term.

If my Worcester boiler is showing a C1 264 fault code, what does this mean?


When a Worcester boiler shows the C1 264 fault code, the problem relates to the fan.

The fan on your boiler helps push harmful gases up the flue and out of your property.

For the boiler to fire up, the PCB needs to recognise that the fan is running. If it’s not running, the boiler could be dangerous.

Problems with fans range from the unit being faulty, communication issues with the PCB, or the incorrect fan speed being set.

If the unit is faulty, there’s a good chance it will simply stop even when it’s meant to be running. The boiler’s PCB recognises this, locks out and displays the C1 264 fault code.

An emergency electrician will be able to determine if it is the fan is faulty.

If the fan is getting power, they’ll need to check that it’s not the boiler’s PCB that is causing the issue. If the PCB is faulty, it might be displaying the C1 264 fan fault (incorrectly), even if the fan is working perfectly.

Finally, an emergency boiler engineer will be able to check the fan speed. If the fan speed has been set too low, the air pressure switch will notice that air pressures aren’t correct in the boiler.

The gases aren’t being expelled quick enough from the boiler. This is potentially dangerous and will lead to the boiler locking out.

What does the C6 fault code mean on my Worcester boiler?


The C6 fault code on your Worcester boiler means that the fan speed is too slow/too fast.

There should be another code attached to the C6. If it’s 215 the fan speed is too fast. If it’s 216, that means that the fan speed on your boiler is too low.

The C6 216 fault code is the most common (fan speed is too low). You’ll need to call an emergency boiler engineer to come and check the fan speed. Sometimes other issues (such as a faulty PCB) could mean that the fault code being displayed, isn’t correct.

The fan on your boiler takes harmful gases out of your property. If it isn’t running quickly enough, the boiler could be dangerous. The air pressure switch is the sensor that recognises that air pressure is incorrect and as a result, it locks out the boiler and displays a fault code.

If the boiler engineer determines that your fan speed is too low, they’ll be able to increase the fan speed to work in line with your boiler.

You shouldn’t reset your boiler to try and clear the fault, as this could be dangerous. Instead, let your heating engineer fix the fault and they’ll reset your boiler on your behalf.

If the C7 fault code is being displayed on my Worcester boiler, what is the cure?


If the C7 fault code is displayed on your control panel, the fault lies with the fan, or blocked air flow. They’ll also be a cause code on the display panel which will either be 214 (fan fault) or 217 (fan fault/air flow blockage).

The first thing your emergency boiler repair engineer needs to do is to check that the fan is getting power. If the fan isn’t getting power, it won’t be able to push harmful gases out of the flue. This makes the boiler dangerous, the PCB recognises this and locks out the boiler as a safety precaution.

The second potential cause is that there’s a blockage relating to air flow. This could be the condensate pipe (common in cold weather), or the flue. If you have a vertical flue that doesn’t have a flue guard fitted, there’s a chance that debris has made its way into the flue. This stops gases being vented from the boiler (and your property).

If it’s the condensate pipe, the boiler engineer will need to thaw out the pipe and reset the boiler.

If the flue has debris in it (or has broken apart), the blockage needs to be cleared (or a new flue fitted) before the boiler can be reset to clear the C7 fault code.

My Worcester Bosch boiler is displaying the D1 fault code, what does this mean?


The D1 fault code on Worcester Bosch boilers relates to a problem with the return sensor.

The return sensor on your boiler monitors the temperature of water after it’s travelled around the heating system. As it travels around pipework and radiators, it loses temperature. So, it’s returning to the boiler to be reheated.

The most likely cause of the D1 fault code being displayed is a faulty NTC return thermistor. NTC thermistors are not particularly expensive to replace. So, instead of paying a boiler engineer to fix the thermistor, it’s much wiser to just fit a replacement.

The replacement shouldn’t take more than a couple of hours (although, these are not parts that a boiler engineer is likely to have on their van, so they’ll need to be ordered from a plumbing merchant).

However, if your emergency boiler engineer notices moisture below the boiler or after removing the casing, it’s likely the NTC thermistor has moisture on it. This can be easily removed, but it’s likely that this moisture has come from a boiler leak.

So, the most important thing to do first is to find and fix the leak on your Worcester boiler. This could be as simple as a loose connection, or it could be something more complex such as a leaking heating pump.

What does the E5 fault code mean on my Worcester boiler, and is it easy to fix?


On your Worcester boiler, there is something called an NTC thermistor. There is one fitted on the flow (water leaving the boiler) and the return (water returning from the heating system, to the boiler).

The E5 fault code relates to the flow thermistor logging temperatures well above what it should be.

A 24 hour boiler engineer will be able to determine whether the problem lies with the NTC thermistor by testing it using it with a multi-meter. If the NTC thermistor is faulty, the readings it’s giving could be false.

If the readings are correct, they’ll need to look for other obvious faults, such as a broken heating pump. If the pump speed is set too slow, or the pump is partially seized, this is going to lead to a circulation fault.

Water is staying in the boiler too long, overheating and that’s what is causing the boiler to lock out. The pump’s speed needs to be adjusted, or the seizure needs to be fixed.

Typically, we find that seizures are due to a seized shaft or bearings. Many pump manufacturers produce service kits, and a boiler engineer can use these to recondition your pump.

However, if your pump is particularly old, it might be worth considering a replacement rather than a repair.

If my Worcester Bosch boiler is showing the E9 fault code, what does it mean, and what’s the cure?


When a Worcester boiler shows the E9 fault code, it means there is a problem with the heat exchanger overheating.

Alongside the generic E9 fault code, the display panel will also show either the 219, 220, 221 or 224 cause code. These will help your emergency boiler engineer figure out the exact problem.

The first thing your boiler engineer will need to check is that the safety sensor isn’t at fault. This is the component that determines if the heat exchanger is overheating. So, if the safety sensor is faulty, the temperature readings it’s feeding back to the PCB could be incorrect.

A simple replacement is needed if your engineer determines this as being the problem.

The next thing to check is that there isn’t limescale build-up on the heat exchanger. Limescale on the heat exchanger will create hot spots, and this leads to water being overheated. More importantly, these hot spots can lead to the heat exchanger cracking over time.

Assuming the heat exchanger isn’t already cracked, it needs to be removed and cleaned. The boiler engineer will then need to hot flush the system using limescale remover, and then top up the system using central heating inhibitor as well as fitting a scale reducer. These are all preventative measures to stop the issue happening again.

My Worcester boiler is showing the EA 227 fault code, what does it mean?


When the EA 227 fault code is displayed on Worcester boilers, it means there’s been no flame detected after four ignition attempts. As there’s a potential ignition or gas supply issue, the boiler locks out as a safety precaution.

The most probable cause is a gas supply issue. For instance, in colder weather, the regulator on the gas meter might become frozen. If this is the case, the supply of gas isn’t going to be high enough for the boiler to ignite.

But the gas supply issue could be in the boiler itself as the jet on burners is prone to getting blocked.

As these jets are extremely small, so even the tiniest piece of debris (a small piece of carbon for instance) could block the jet. This is going to restrict gas to the burner and cause the EA 227 fault code to be displayed.

So, your boiler engineer will need to check that the meter’s regulator isn’t frozen. And from there, they’ll need to ensure that the jet isn’t blocked.

If neither of these are the problem, the cause could be moisture on electronics. This can cause boilers to work intermittently. Your engineer will need to determine the source of moisture (i.e. a leak), fix it and then dry out all electronic components in your boiler.

Finally, your engineer can check that it’s not the gas valve causing the supply issue. A faulty, incorrectly adjusted or sticking gas valve could be the cause of the gas supply issue.

Once fixed, your engineer can then reset your boiler to clear the EA 227 fault code.

More on Faulty Gas Valves By Clicking Here.

Why is my Worcester Bosch boiler showing the EA 229 fault code, and what is the cure?


The EA 229 fault relates to a flame detection issue, like the EA 227 fault code.

However, the EA 229 fault code directly relates to flame loss (i.e. there was a flame, and it’s disappeared) rather than the EA 227 fault that relates to a lack of flame (i.e. the boiler didn’t manage to ignite as a flame never existed).

The symptoms are similar, but the issue has presented itself whilst the boiler was working.

A typical place to start for your emergency boiler engineer is going to be the gas valve. If the valve is incorrectly adjusted or sticking, this can lead to an inadequate supply of gas, and this will lead to the flame going out.

Although a possible cause could be intense winds, it’s unlikely.

The more obvious cause is that the fan speed isn’t set high enough. A small back draft from wind could blow out the flame if the fan is operating at the incorrect speed.

For this reason, a boiler repair engineer will check that first the fan is operating correctly. Then, they’ll ensure that the fan speed is set correctly. If it’s not, the fan speed can be adjusted.

Another potential cause (although, unlikely), is debris in the flue. This is most likely if you have a vertical flue (going through your roof) without a flue guard fitted. If this is blocked with debris, it needs to be cleared and then refitted to fix the EA 229 fault code.

If my Worcester Bosch boiler is showing the EA 234 fault code, what does it mean, and can it be fixed?


The EA 234 fault code on Worcester Bosch boilers relates to a gas valve problem.

Your heating engineer will be able to first, check that the coil isn’t disconnected. If the coil isn’t disconnected, the fault is going to lie with the gas valve itself.

For valves that are particularly old, it’s likely that they are slowly seizing. This might mean that they don’t open or close fully, and that’s going to lead to a gas supply issue.

Your boiler engineer will be able to work the valve free, rather than replacing the whole unit.

If the gas valve isn’t seized, they’ll need to check the adjustment of the valve. If the valve isn’t adjusted correctly, it could be supplying the boiler with too much/too little gas, and that’s not going to allow the boiler to operate correctly.

If the valve itself is faulty, a replacement can be fitted. Expect to pay around £300 and for the job to take around 1 working day to complete.

My boiler is showing the EA 338, what do I need to do to get this fixed?


The EA 338 fault code relates to a boiler that is showing low water pressure. That’s going to create a dry fire in the heat exchanger and the pump to run dry. If the boiler continued to operate it would cause damage, so the boiler locks out to preserve expensive boiler parts.

The pressure your boiler is showing and the amount of water in your heating system are connected. You need to top up the boiler using the external filling loop.

Your boiler will operate best at 1.3 bar. Once you’ve topped this up, the boiler pressure shouldn’t drop. If the pressure on your boiler is consistently dropping, then there is a leak in the system somewhere.

So, top up your boiler, but if you notice pressure dropping, you’ll need to call an emergency boiler repair engineer. They’ll need to find and fix the leak before topping up your boiler again to clear the EA 338 fault code.

If you keep topping up your boiler pressure, this could lead to property damage. Water is leaking somewhere, and if it’s consistently leaking on plaster or floorboards, this could lead to expensive repair bills.

Other boiler issues relating to other manufactures


For more boiler issues then please visit the Boiler Problems And Cures page.