204 O High
Your boiler has stopped running because the water inside it has become hotter than the temperature you have requested.
Technical description: Current primary water temperature higher than set value
Typical repair cost: £100-280 (including labour)
DIY fix possible
Check that your radiator valves are open to allow water to circulateEnsure there is no air trapped in your radiators by bleeding themCheck that the boiler pressure gauge is between 1 and 1.5 barReset the boiler to see if the fault clears
Protect yourself from future repair bills
A boiler cover plan would cover faults like 204 O — no call-out fees, no surprises.
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Parts commonly replaced
- Circulation Pump
- Temperature Sensor (NTC Thermistor)
- Diverter Valve
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