S.39 High
Your boiler has temporarily stopped running because an external safety device, such as a condensate pump or a pipe thermostat, has detected a potential issue and sent a signal to shut the burner down.
Technical description: Burner off contact has been triggered this could be because of contact thermostat or condensate pump
Typical repair cost: £100-220 (including labour)
DIY fix possible
Check if your external condensate pump is plugged in and turned on.Inspect the condensate pump reservoir; if it is full, the pump may be blocked or broken.If you have underfloor heating, check if the limit thermostat has tripped and reset it if necessary.
Protect yourself from future repair bills
A boiler cover plan would cover faults like S.39 — no call-out fees, no surprises.
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Parts commonly replaced
- Condensate pump
- External limit thermostat
- Wiring harness
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