Worcester Bosch Boiler C7 Fault Code
The Worcester fault code C7 fan, airflow or blockage Q & A or require an engineer for an emergency boiler repair.
The Worcester Boiler Fault Code C7 Error Common Q & A
Just below, we have a list of common questions relating to the C7 fault code on the Worcester Bosch Boiler.
- What does the C7 fault code mean on my Worcester Bosch boiler?
- Why does my boiler lock out when the C7 fault code is displayed?
- Can I reset my Worcester Bosch boiler to clear the C7 fault code?
- If my boiler is showing the C7 214 fault code, what could be causing it?
- How will an engineer know if the fan is faulty?
- How much does it cost to replace a fan on a Worcester boiler, and how long will it take to fit?
- If faulty electrics are the problem, what is the solution to clear the C7 fault code?
- What does the PCB do on my boiler, and how can this cause problems with the fan?
- Is it possible to diagnose and repair a faulty PCB?
- How much will a new PCB cost, if that’s what’s causing the C7 fault?
- What can cause an airflow problem, and the C7 217 fault code to be displayed?
- How could the flue cause the C7 217 fault code to be displayed?
- What issues can arise from the burner, and how can it cause the C7 fault?
- How can the air pressure switch cause the C7 fault code to be displayed?
- What’s the cost of a new air pressure switch for a Worcester Bosch boiler?
What does the C7 fault code mean on my Worcester Bosch boiler?
Worcester Bosch have a 2-piece fault code system.
The first is a fault code, in this case it’s C7.
The second is a cause code. This helps to highlight the exact fault with the boiler.
In the case of a C7 214 fault code, the boiler’s fan is not running.
However, if your Worcester Bosch boiler is showing a C7 217 fault code, the cause could either be:
- The fan is not running
- Airflow restriction or blockage in the boiler
Due to the C7 217 fault code being less specific, the diagnostic for this boiler fault is more difficult.
Why does my boiler lock out when the C7 fault code is displayed?
The fan on your boiler helps to vent dangerous gases from your boiler. These gases are pushed up the flue (the large white pipe fitted on the exterior of your property) by the draught from the fan, and out of your property.
When these gases are not vented, the boiler becomes dangerous, and locks out as a safety precaution.
The PCB (printed circuit board) receives an electrical signal from the air pressure switch. This switch monitors the air pressure in your boiler. When the pressures aren’t within working tolerance, that’s the sign that a fault is present, and it locks out.
It’s the PCB that then recognises the exact fault, and shows the fault code (in this case, the C7).
This fault isn’t the same as a C6 fault code (although it’s possible you may have noticed this code appear in the past).
Instead, the C6 relates to a fan issue, but it’s the fan speed causing problems (too high/too low), rather than it not working completely.
Can I reset my Worcester Bosch boiler to clear the C7 fault code?
All boiler lock outs should be taken seriously. The boiler could be dangerous, so it needs to be fixed by a qualified Gas Safe engineer. They’ll be able to find and fix the problem.
Once they’ve fixed the fault, they can reset the boiler and test it to make sure there are not further issues.
If my boiler is showing the C7 214 fault code, what could be causing it?
The C7 error with a 214 cause code, means your fan isn’t running.
The most obvious issues causing a fan not to run would be:
- A faulty fan
- Faulty electrics to and from the fan
- A faulty PCB
- Gas valve
- Diverter valve
- Burner
- Heating pump
- Flue
- Burner
- Air pressure switch
How will an engineer know if the fan is faulty?
The fan’s electrics will need to be tested with a multi-meter. If the wiring and connections are working, then it’s the fan unit that is to blame.
The engineer will need to check that the fan isn’t seized, rather than completely broken.
In some cases, a fan’s shaft can seize due to worn or degraded bearings. Although the bearings and shaft could be replaced, it would make much more sense to replace the whole unit.
A new fan will last 5 years or longer, whereas a reconditioned fan could fail at any time.
How much does it cost to replace a fan on a Worcester boiler, and how long will it take to fit?
We’d expect a replacement fan to cost around £250.
The cost will vary depending on the exact model of boiler, and therefore the price of the fan.
You should expect a Gas Safe engineer to diagnose the problem and replace the fan within 1 working day.
If faulty electrics are the problem, what is the solution to clear the C7 fault code?
Although all electrical wiring and connections need testing with a multi-meter, it’s usually obvious what’s causing the problem.
We find that most of the time it’s either problems with damaged wiring, or loose connections.
Replacing sections of wiring, or re-securing connections would solve the issue in this case.
What does the PCB do on my boiler, and how can this cause problems with the fan?
The PCB on your Worcester boiler is the most vital component. It’s an electronic circuit board that gives and receives signals to all electrical components.
So, it does things like telling the gas valve to open, the spark generator to ignite, the fan to turn on, and receives signals from the air pressure switch to ensure the boiler is operating safely.
When the PCB has issues, it may give or receive the wrong signals. That means it may tell other components to start/stop working or open/close, when they shouldn’t.
In this case, the PCB would cause your boiler to work intermittently. Because, a boiler won’t ignite until the fan is working (so the draught is ready to expel flue gases).
So, if the PCB isn’t giving the fan the signal to start up, the air pressure notices theirs is no draught, tells the PCB it’s not safe to fire, and the boiler won’t ignite.
Instead, it will lock out and show the C7 214 or C7 217 fault code.
Is it possible to diagnose and repair a faulty PCB?
All electrical problems in a boiler are hard to diagnose. The boiler thinks there’s a problem with the fan, but it could just as easily be the PCB giving the fan the wrong signals.
After all, if the PCB is faulty there’s a good chance it’s showing the wrong fault code to begin with.
The PCB can be diagnosed by testing all electrical wiring and connections with a multi-meter.
And whilst PCBs can be repaired, it’s a notoriously difficult task. So, it’s more cost efficient to replace them.
How much will a new PCB cost, if that’s what’s causing the C7 fault?
Investing in a new fan isn’t something you should take lightly. Depending on your boiler, you should expect it to cost in the region of £500, and take a day to replace.
If your boiler is over 10 years old, it’s rarely worth investing in a new fan. The energy savings you’ll get from a new boiler, combined with a long warranty where you won’t be subject to expensive repair bills, is a much wiser place to put your money.
So, if your Gas Safe engineer feels the PCB is the issue and you’re considering replacing the PCB, check other expensive part’s condition too.
The most expensive parts include the:
If the PCB and two or more of these items are in bad condition, it’s not worth fixing your boiler.
What can cause an airflow problem, and the C7 217 fault code to be displayed?
The diagnostic for the C7 217 fault code is the same as above, to initially determine if the fan is not running.
However, Worcester list a blocked airflow as the potential issue, and this could be down to lots of issues including the:
How could the flue cause the C7 217 fault code to be displayed?
Just like the boiler won’t fire up if the fan isn’t running, it won’t if the flue is blocked.
This is uncommon, but it’s not unheard of. The most common reason a flue will get blocked is if a vertical flue (this comes out of the roof) has been fitted, without a flue guard.
These guards are designed to keep debris out of the flue. If one isn’t fitted, there’s a chance that this debris has made it into the flue, and isn’t allowing flue gases to escape from your property.
What issues can arise from the burner, and how can it cause the C7 fault?
A completely faulty burner won’t cause a C7 fault, as that’s an ignition related issue, rather than an air flow problem.
However, if a burner has a blocked pilot jet, the flame may be weak. A small back draught in the flue, combined with a low fan speed would change the air pressure which makes the air pressure switch thinks there’s a blockage.
In this case, the jet in the burner needs to be cleaned or replaced, so it can supply the burner with a steady flow of gas.
How can the air pressure switch cause the C7 fault code to be displayed?
It’s more common to see a problem with an air pressure switch, rather than the flue.
Like any electrical component, air pressure switches can fail. This process is going to be sped up if it’s had water damage (from a small internal boiler leak for instance).
If the air pressure switch isn’t working correctly, it’s going to give intermittent or incorrect signals to the PCB. This could cause the PCB to think the boiler is unsafe, even when it isn’t.
In this case, the air pressure switch will need to be replaced.
What’s the cost of a new air pressure switch for a Worcester Bosch boiler?
Depending on the exact model of boiler, you should expect to pay £250 for an air pressure switch replacement.
As with the PCB, have your engineer check other expensive boiler components too. It might be that they’re degrading fast, and a new boiler is more cost effective.
And, if the Gas Safe engineer does suspect water damage - the leak needs to be found and fixed before replacing the switch.
Other Worcester boiler issues
More more boiler issue regarding the Worcester Bosch the please visit the Worcester Boiler Problems And Cures page.