F.20 High
Your boiler has shut down because it has detected it is getting too hot, usually caused by a lack of water flow or a blockage in the system.
Technical description: Safety switch off temperature limiter
Typical repair cost: £100-£350 (including labour)
DIY fix possible
Check if your radiator valves are openCheck the boiler pressure gauge and top up if it is below 1.0 barPress the reset button (flame symbol) to see if the fault clears
Protect yourself from future repair bills
A boiler cover plan would cover faults like F.20 — no call-out fees, no surprises.
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Parts commonly replaced
- Overheat Thermostat
- NTC Temperature Sensor
- Circulation Pump
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