S.40 Low
Your boiler has detected a minor inconsistency in its temperature readings and has slightly reduced its power to ensure it continues to provide heating and hot water safely.
Technical description: Comfort safety mode active
Typical repair cost: £0-120 (including labour)
DIY fix possible
Check that all radiator valves are fully openEnsure the boiler pressure is between 1.0 and 1.5 bar on the digital displayReset the boiler by pressing the flame symbol button for three seconds
Protect yourself from future repair bills
A boiler cover plan would cover faults like S.40 — no call-out fees, no surprises.
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Parts commonly replaced
- No parts usually required
- NTC Temperature Sensor
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