D.33 Medium
Your boiler is struggling to match the correct fan speed needed to safely clear exhaust gases, which may lead to the system pausing for safety.
Technical description: Fan speed target value
Typical repair cost: £180-450 (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 D.33 — 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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