Verified boiler fault code
Worcester Bosch C6 Fault Code (Greenstar FS CDi ErP Regular)
Fan speed too low.
Safety disclaimer
Fault code summary
- Manufacturer
- Worcester Bosch
- Fault code
- C6
- Fault type
- Fan, Flue
- Severity
- Not specified
- Reset
- Not specified
- Applicable models
- Greenstar FS 30CDi ErP Regular, Greenstar FS 42CDi ErP Regular
Quick answer
Fan speed too low.
What does this fault code mean?
Fan speed too low.
Common causes
- Fan speed is below the expected value.
Symptoms
This information was not provided in the verified manufacturer source.
What can the homeowner safely check?
This information was not provided in the verified manufacturer source.
Boiler reset information
Reset information was not provided in the verified manufacturer source. Do not repeatedly reset an unresolved fault.
When should I call an engineer?
Contact a suitably qualified heating engineer when the fault persists, the boiler locks out, or the manufacturer instructions do not resolve it. For gas appliance work in the UK, use a Gas Safe registered engineer.
Engineer diagnosis
- Check fan operation and the flue/air path.
Applicable boiler models
Related fault codes
- A7 — Greenstar FS CDi ErP Regular
Hot water NTC sensor defective.
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Code plug not detected.
Read fault code - d5 — Greenstar FS CDi ErP Regular
Condensate pump fault.
Read fault code - E2 — Greenstar FS CDi ErP Regular
CH flow NTC sensor defective.
Read fault code - E9 — Greenstar FS CDi ErP Regular
Safety temperature limiter in the CH flow has tripped.
Read fault code - EA — Greenstar FS CDi ErP Regular
Flame not detected.
Read fault code - F0 — Greenstar FS CDi ErP Regular
Internal error.
Read fault code
Manufacturer documentation
Greenstar FS 30CDi & 42CDi ErP Regular user instructionsC6 | Fan speed too low.
Last verified
2026-09-12
Frequently asked questions
What does Worcester Bosch C6 mean?
Fan speed too low.