Gas valve fault: gas furnace codes by brand

A gas valve, solenoid or gas/air mixing (venturi) control is not responding correctly.

Brand	Code	Meaning	What you can do
Carrier	21	Gas heating lockout, fault in the gas valve circuit	Safe checks first, then a pro
Carrier	22	Flame sensed while the gas valve is off	Safe checks first, then a pro
Carrier	35	Modulating gas valve not communicating	Call a pro
Carrier	21.1	24 volts sensed at the gas valve when there should be none	Safe checks first, then a pro
Carrier	22.1	Flame proved while the gas valve is off	Safe checks first, then a pro
Carrier	35.1	Modulating gas valve not communicating	Call a pro
Goodman	ECF	Gas valve stepper motor communication error	Call a pro
Goodman	EEb	Gas valve not powered when it should be	Call a pro
Goodman	EEC	Gas valve powered when it should be off	Safe checks first, then a pro
Goodman	1 red flash	Ignition failure or gas valve fault (depends on model)	Safe checks first, then a pro
Goodman	10 red flashes	Power supply problem or gas valve fault (depends on model)	Depends on your model