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Worcester Bosch Boiler C6 Fault Code

The Worcester fault code C6 fan fault Q & A or require an engineer for an emergency boiler repair.


The Worcester Boiler Fault Code C6 Error Common Q & A

Just below, we have a list of common questions relating to the C6 fault code on the Worcester Bosch Boiler.

Worcester Boiler C6 Fault Code Error
  • What does the C6 fault code mean on my Worcester boiler?
  • What does the fan do in my boiler?
  • Why does my boiler lockout if the fan speed is too low?
  • My fan isn’t running, what is the problem?
  • What is the DIY fix for a C6 fault code on a Worcester Bosch boiler?
  • Can the fan speed be adjusted to clear the C6 fault code?
  • What happens if adjusting the fan speed doesn’t clear the C6 fault code?
  • How will a boiler engineer know if the fan is faulty?
  • If I need a new fan for my Worcester boiler, how much will it cost?
  • If the wiring and connections are loose or damaged, can they be fixed?
  • What is the PCB on my boiler?
  • Can a faulty PCB be fixed?

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

The C6 fault code on Worcester Bosch boilers relates to a fan fault.

There are two additional codes that help determine the exact problem:

  • 215
  • 216

When the 215 code is attached to the C6 error, the PCB has detected that the fan speed it too low. This is the most obvious and common cause of a C6 fault code showing on Worcester Bosch boilers.

However, if the C6 is shown with a 216 error, that’s a sign of a fan speed that is too high.


What does the fan do in my boiler?

Boiler fans don’t operate in the way many people expect. They do not cool down the internal components of a boiler.

Your boiler produces a range of harmful gases as it operates. Newer boilers will be condensing, and some of the gases escape via the condensate pipe. This is the small white pipe (usually 21.5mm in diameter) on the exterior of your property – you may have noticed this dripping.

The uncondensed gases escape via the flue. This is the much larger white pipe on the exterior of your property.

Before a boiler ignites, the PCB (the boiler’s circuit board) needs to recognise that the fan is operational.

The fan creates a draft that pushes gases up and out of the flue; keeping you safe.

Why does my boiler lockout if the fan speed is too low?

The component you hear fire into life before any others (even the ignition), is the fan. If the fan isn’t running, a boiler becomes dangerous, so it locks out.

In this case, it shows the C6 215 error as a warning that it’s the fan causing the issues.

Although a fan that’s running at low speed will create a small draught allowing flue gases to escape, it won’t allow all of them to escape.

The boiler locks out as a safety mechanism, to protect you and others inside the property.

My fan isn’t running, what is the problem?

If you don’t hear your fan start up, then this should generate a different fault code on your boiler’s display panel.

We’d expect to see the C7 fault code, with a 214 error message. This is the error code for a fan not running, and slightly different to the C6 215 which shows the fault as being a low fan speed.

What is the DIY fix for a C6 fault code on a Worcester Bosch boiler?

Once a boiler’s casing has been removed, touching any components is classed as working on a gas appliance. The only people qualified to be doing this, are Gas Safe engineers.

Some fixes for boilers and heating are simple, easy and safe. One example might be topping up the boiler’s pressure.

However, when we are talking about a combustion based gas appliance, and a component (the fan) that helps get rid of harmful gases; there’s no safe DIY fix.

You should call a Gas Safe engineer to help you right away.

Don’t reset the boiler to try and clear the fault. In fact, it would be much safer to turn off the appliance.

Can the fan speed be adjusted to clear the C6 fault code?

Whether your fan problem relates to running too fast, or too slow, it can be adjusted.

A boiler engineer will need to match up the 215/216 fault codes to determine which of these is the causing the issue, and why.

If the fan has suddenly started running too fast, that’s a sign of an electrical error.

What happens if adjusting the fan speed doesn’t clear the C6 fault code?

If the fan has been correctly adjusted but the error is still showing after a reset, there are a few possible scenarios:

  • The fan is faulty
  • The wiring to the fan is loose or damaged
  • The PCB is malfunctioning

How will a boiler engineer know if the fan is faulty?

The first thing your boiler engineer will look out for, is age. A boiler that’s less than 10 years old, won’t usually have a faulty fan.

However, they’ll need to test all electronics to and from the fan. If the wiring and connections are not damaged, faulty, or loose, it’s likely the fan itself is causing the issue.

There are several things that can go wrong with a fan.

An old one that’s been subject to years of use, could have worn bearings or a damaged shaft. This would make the fan stiff, not turn correctly, and not able to get up to the speed that the flue requires it too.

The bearings on the fan could be replaced. However, due to the cost of labour (and time taken) to diagnose the fault, it makes sense to replace the whole unit.

If I need a new fan for my Worcester boiler, how much will it cost?

We can offer a guestimate. But, bear in mind that a fan for one boiler might be £75 (parts only), and another might be £200.

On average, a replacement fan is likely to cost £250. In terms of a boiler repair for something so crucial, this is a worthy investment, assuming one thing; other expensive components are in good condition.

Before spending £250+ on your boiler, get your Gas Safe engineer to check the condition of the heat exchanger, pump, and PCB.

If any of these parts look like they could fail soon, investing in a new boiler would be a better option long-term.

If the wiring and connections are loose or damaged, can they be fixed?

When testing to see if the fan is faulty, your engineer will check all wiring and connections to the fan. If they’ve determined these as being the fault rather than the fan, they can usually be repaired.

Where their multi-meter is showing sections of wiring as faulty in the circuit, these can be replaced.

And typically, loose connections can be easily re-secured.

What is the PCB on my boiler?

The PCB (printed circuit board) is the heart of a boiler. It gives and receives signals to any component that’s connected via electronics. This includes the:

  • Fan
  • Pump
  • Burner
  • Thermostat
  • Diverter valve
  • Gas valve

Basically, every single vital component on your boiler, is connected to the PCB. So, if the PCB fails, it’s easy to misdiagnose other parts.

For example, in this case, it may seem like the wiring to the fan, or the fan itself is to blame.

However, it could be a faulty PCB that’s not detecting the correct fan speed, or not recognising when the fan is on or off.

Can a faulty PCB be fixed?

A simple case of loose connections can be easily fixed.

However, what we find is that most PCB errors stem from old-age, or water damage. This might have led to burnt out connections, or a cracked circuit board. These are two things that are not easily fixed.

It’s important to get your Gas Safe engineer to assess the PCB in detail, but it’s not usually good news.

The PCB is not just the most important part on your boiler, it’s also the most expensive. A replacement could cost over £500, and it’s rarely worth spending that kind of money on an old boiler.

Other Worcester boiler issues

More more boiler issue regarding the Worcester Bosch the please visit the Worcester Boiler Problems And Cures page.