F5 High
Your boiler has switched itself off because it has reached an unsafe temperature to protect the internal components from damage.
Technical description: Overheat fault
Typical repair cost: £120-300 (including labour)
DIY fix possible
Check that all radiator valves are fully open to allow water to circulateEnsure the boiler pressure gauge is between 1 and 1.5 barPress the reset button once to see if the fault clears after the system has cooled down
Protect yourself from future repair bills
A boiler cover plan would cover faults like F5 — no call-out fees, no surprises.
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Parts commonly replaced
- Overheat Thermostat
- Circulation Pump
- Main Heat Exchanger
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