125 High
Your boiler has detected that water isn't moving through the system properly, which is causing it to overheat and shut down for safety.
Technical description: Water circulation fault
Typical repair cost: £150-£350 (including labour)
DIY fix possible
Check that your system pressure is between 1 and 1.5 bar on the pressure gaugeEnsure all radiator valves and isolation valves under the boiler are fully openBleed your radiators to remove any trapped air pockets
Protect yourself from future repair bills
A boiler cover plan would cover faults like 125 — no call-out fees, no surprises.
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Parts commonly replaced
- Circulating Pump
- Pump Lead
- Main Heat Exchanger
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