12 High
Your boiler has shut itself down for safety because it failed to light or detected a general system failure.
Technical description: Default lockout
Typical repair cost: £100-350 (including labour)
DIY fix possible
Check that your gas pre-pay meter has credit (if applicable).Ensure your external gas emergency control valve is in the 'on' position.Press and hold the reset button for five seconds to see if the boiler restarts.
Protect yourself from future repair bills
A boiler cover plan would cover faults like 12 — no call-out fees, no surprises.
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Parts commonly replaced
- Ignition Electrode
- Gas Valve
- PCB (Printed Circuit Board)
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