Furnace LED shows code 42 (inducer motor fault). Furnace will not ignite; inducer may not start or may start then stop.

Safety first: Turn off power and gas. The inducer is part of the combustion system.

• Listen for inducer: With a call for heat, listen for the inducer fan starting. If you hear only a hum or nothing at all, the motor may be failed.
• Inspect inducer housing: Remove the burner door and visually inspect the inducer assembly for cracks, water leaks, or debris.
• Check condensate lines: On condensing models, ensure the condensate drain from the inducer/collector box is clear. A backed-up drain can flood the inducer.
• Verify power to inducer (advanced): A technician can check for 120V at the inducer motor leads when there is a call for heat. If voltage is present but the motor does not run, the inducer needs replacement.

Inducer replacement involves sealing the combustion chamber and vent connections; have this done by a qualified HVAC technician.