4 red flashes High
Your boiler's fan is not spinning or communicating correctly with the system, preventing the boiler from starting safely.
Technical description: Fan fault
Typical repair cost: £250-£450 (including labour)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Protect yourself from future repair bills
A boiler cover plan would cover faults like 4 red flashes — no call-out fees, no surprises.
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Parts commonly replaced
- Fan assembly
- Printed Circuit Board (PCB)
- Wiring harness
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