BoilerFaultCodesSime Format B Combi Fault codes & diagnostics
0 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Combi Natural Gas 1995-2005 Discontinued
GC Numbers 47-283-0747-283-08
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Status & diagnostic codes 8 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.
8 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.
25 BF Status Your boiler has detected an issue with the air supply or exhaust system, meaning it cannot safely vent waste gases and has shut down to prevent a hazard. 30 BF Status Your boiler has detected an issue with the air intake or exhaust flue system, which prevents it from operating safely. 80 B Status Your boiler is not detecting a flame, which means it has safely shut down because it cannot ignite the gas to provide heat or hot water. 100 B Status Your boiler is not detecting the necessary water pressure to operate safely and will not provide heating or hot water until this is corrected. C12 Diagnostic Your boiler has detected an issue with the air supply or exhaust system, meaning it has shut down to keep your home safe. C32 Diagnostic Your boiler's external temperature sensor is not communicating correctly, which may cause your heating system to run inefficiently or shut down. C42 Diagnostic Your boiler has detected an issue with the external sensor used to monitor the outdoor temperature or flue conditions, causing it to stop functioning correctly. JP4 Diagnostic Your boiler has detected an incorrect setting regarding the type of fuel it is using, such as a mismatch between mains gas and bottled gas.