Lennox Combi Boiler Error Codes
Lennox GWM/GWB boilers report faults on the integrated control. Note the code or LED flash pattern before calling.
This is not a DIY repair
Combi boilers are gas-fired appliances regulated under the BC Safety Standards Act. Opening the unit, touching the gas valve, or working on the flue without a valid BC gas-fitter licence is both unsafe and illegal. Diagnosing the fault is helpful — fixing it should always be left to a certified technician.
Call 778-909-5731Lennox fault codes (10)
Code 1UrgentIgnition lockout — no flame established.Code 2UrgentFlame loss during operation.Code 3UrgentHigh-limit / overheat.Code 4ModerateSupply temperature sensor fault.Code 5ModerateReturn temperature sensor fault.Code 6UrgentPressure switch / air proving fault.Code 7UrgentBlower/fan fault.Code 8ModerateLow water pressure.Code 9UrgentGas valve fault.Code 10ModerateControl board internal fault.