J6-20 High
Your boiler has detected that the water returning to the unit is too hot, which has caused it to shut down to prevent damage.
Technical description: Return temperature sensor overheating due to a blocking fault or a lockout error – try resetting the boiler
Typical repair cost: £120-280 (including labour)
DIY fix possible
Ensure all radiator valves are fully open to allow water to circulate.Check that the central heating system pressure is between 1.0 and 1.5 bar.Press the Reset button on the boiler control panel to clear the lockout.
Protect yourself from future repair bills
A boiler cover plan would cover faults like J6-20 — no call-out fees, no surprises.
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Parts commonly replaced
- Return temperature sensor (NTC)
- Circulation pump
- Main Heat Exchanger (if blocked)
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