Worcester Bosch C7 fault codewhat it means and how to fix it
The fan is not running at all, as distinct from running at the wrong speed. The burner is locked out until it is fixed.
Take care
Get a Gas Safe registered engineer to look at your Worcester Bosch C7
Gas Safe Register engineers only. No obligation.
What C7 means
Worcester separate two fan conditions and it is worth knowing which you have. C6 means the fan speed is wrong — too low, or on some models too high. C7 means the fan is not running. That distinction narrows the diagnosis usefully: a fan turning at the wrong speed is usually a worn fan or a flue restriction changing its loading, whereas a fan not turning at all is more often electrical — a failed motor, a lost supply, or a broken connection. The interlock behind both is the same and it is absolute. No condensing appliance will open its gas valve without proof that the fan is clearing combustion products through the flue, and there is no way to run around that. What a householder can usefully contribute is history: whether the appliance has been getting noisier over recent months, and whether anything obvious is blocking the flue terminal when viewed from the ground.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Fan motor failed | The most direct explanation for a fan that is not turning. Often the end point of months of increasing start-up noise. | Common |
| Fan seized mechanically | Bearings that have finally bound up rather than merely worn. Sometimes accompanied by a brief hum as the appliance tries to start it. | Common |
| Wiring or connector failure | No supply reaching the fan, or a broken connection in the harness. Considerably cheaper than a fan and worth eliminating first. | Occasional |
| Control board not driving the fan | The board is failing to energise it. Diagnosed once the fan and its wiring have been proved. | Occasional |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£200–£450
A replacement fan is typically £300 to £450 fitted on the Greenstar range. A wiring repair is a call-out charge of £80 to £150.
Typical UK prices including parts and labour, updated August 2026. Your quote may differ.
Parts you may need
We may earn a commission if you buy a part through one of these links. It does not change what you pay, and it does not affect which parts we list.
Worcester Bosch Greenstar fan assembly
87161431070£130–£250Authorised Worcester parts distributor
Price checked 5 August 2026
What other owners found
Nobody has shared what worked for them on this code yet. If you have had it, you would be the first — and it genuinely helps the next person.
Related Worcester Bosch fault codes
- C6 224Get it checkedThe fan is not reaching the speed the boiler asked for, so combustion cannot be confirmed as safe and the burner has been prevented from firing.Related: fan and flue
- D5Get it checkedThe condensate pump has failed or cannot discharge. Acidic water will back up inside the appliance, so it needs attention promptly.Related: fan and flue
- E16Get it checkedThe control board cannot confirm the fan is running at the speed it asked for, so it will not let the burner light. This one needs an engineer.Related: fan and flue
- F.32Get it checkedThe fan is not running at the speed the boiler expects, so combustion cannot be verified as safe and the boiler has locked out.Related: fan and flue
- E160Get it checkedThe fan is not running at the speed the appliance expects. Baxi direct engineers to check the fan and its cable, in that order.Related: fan and flue
- F3Get it checkedThe fan is not running at the speed the boiler expects, so it cannot confirm the flue is clearing and has stopped the burner firing.Related: fan and flue
Related guides
Common questions about Worcester Bosch C7
What is the difference between C6 and C7?
C6 means the fan speed is wrong; C7 means the fan is not running. C6 more often turns out to be a worn fan or a flue restriction, while C7 skews towards an electrical failure. Quote whichever number you can actually see, because it changes where the engineer starts.
The boiler was grinding for months before this. Related?
Almost certainly. A fan bearing that grumbles on start-up and quietens as it spins up is wearing out, and a seizure is where that ends. Reporting that noise early turns an emergency into a planned repair.
Can I get heating any other way in the meantime?
Not from the boiler — the fan interlock blocks every burner operation including hot water. A plug-in electric heater for a day is the practical answer.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer technical and service documentation
- Interviews with working engineers
Checked by Technical reviewer (Gas Safe registration to be displayed on appointment) on 5 August 2026.