How to Fix Worcester Bosch C6-266 Fault Code (UK)
Worcester Bosch showing C6-266 — Fan speed. UK diagnosis, likely spare (combustion fan 87172043260) and step-by-step reset.
What the code means
C6-266 on a Worcester Bosch indicates fan speed. The boiler locks out to protect the heat exchanger and, on gas faults, to comply with the Gas Safety (Installation and Use) Regulations. Always reset to confirm the code is live, not historical.
Likely spare
The most common fix is the combustion fan 87172043260. Check the exploded diagram against the GC number on the data plate before ordering — Worcester Bosch revised parts on Worcester Bosch units mid-production.
Fix procedure
Isolate 230V, unclip fan, check tacho signal.
Log the fault and reset. If the code returns within 24 hours, escalate to full electrical diagnosis with a manometer and multimeter.
Frequently asked questions
- Can I reset C6-266 myself?
- You can press the reset button up to 3 times. If C6-266 returns, the boiler needs a Gas Safe engineer — it is illegal to repair gas components without registration.
- Is the part covered under warranty?
- Worcester Bosch standard warranty is 2–10 years depending on model. Registered installations get the full term. Check the sticker inside the case.
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