H.01 – .08 High
Your boiler is overheating because water isn't moving through the system quickly enough to be cooled down.
Technical description: Sensor fault, flow temperature increasing too fast in heating mode or insufficient circulation.
Typical repair cost: £120-350 (including labour)
DIY fix possible
Check that your boiler pressure is between 1 and 1.5 bar on the gaugeEnsure all radiator valves are fully openRestart the boiler using the reset button
Protect yourself from future repair bills
A boiler cover plan would cover faults like H.01 – .08 — no call-out fees, no surprises.
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Parts commonly replaced
- Circulation pump
- Flow temperature sensor (NTC)
- Main heat exchanger (de-scaling)
*Affiliate links — we may earn a commission at no extra cost to you.