H9-01 Low
Your boiler is struggling to understand the outdoor temperature, which may cause your heating to run less efficiently or at the wrong temperature.
Technical description: Outside sensor fault – try resetting the boiler
Typical repair cost: £90-160 (including labour)
DIY fix possible
Locate the reset button (usually a circular arrow or 'R') on the front control panel.Press and hold the reset button for 2 to 3 seconds.Wait for the boiler to restart; if the code reappears, a professional is required to check the wiring.
Protect yourself from future repair bills
A boiler cover plan would cover faults like H9-01 — no call-out fees, no surprises.
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Parts commonly replaced
- External temperature sensor
- Sensor wiring harness
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