9 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: CSI 150
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Your boiler has failed to light, which means you will not have any heating or hot water until the issue is resolved.
Your boiler has detected an internal temperature issue and has locked itself out to prevent overheating.
Your boiler has sensed that it is getting too hot and has shut itself down to prevent damage or safety issues.
Your boiler is struggling to detect the temperature of your hot water supply, so it has stopped providing hot water to prevent internal overheating.
Your boiler's internal thermometer for the central heating system has stopped working correctly, which means the system cannot monitor or control the water temperature.
Your boiler has stopped working because the fan is not receiving the correct electrical power needed to safely clear exhaust fumes.
Your boiler has detected that there is not enough water pressure or flow to operate safely, which is preventing your heating and hot water from working.
Your boiler has shut down because a sensor has detected that the exhaust gases are getting too hot or the sensor itself has failed.
Your boiler has detected that the exhaust gases are not being monitored correctly and has shut down for safety.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes