1A, 1B High
Your boiler has shut down because it is struggling to discharge exhaust fumes safely or is detecting a significant lack of air flow.
Technical description: Burner blocked
Typical repair cost: £120-450 (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 1A, 1B — no call-out fees, no surprises.
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Parts commonly replaced
- Flue gas sensor
- Heat exchanger (cleaning)
- Ventilation fan
- Condensate trap
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