The furnace starts the inducer and ignitor, the gas valve opens briefly, then shuts off with E4; multiple failed ignition attempts occur.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety: Shut off the power and gas before servicing. Allow the burners to cool.
Cleaning and checks:
- Locate the flame sensor on the burner assembly (a small metal rod in front of one burner, connected by a single wire).
- Remove the mounting screw and gently pull out the sensor.
- Clean the metal rod with fine steel wool or a Scotch-Brite pad until it is shiny. Do not use sandpaper that leaves deep scratches.
- Inspect the sensor wire and connector for corrosion or a loose fit at the IFC. Reseat the connector.
- Verify that the burner assembly and furnace chassis have a solid ground connection to the control board (check the ground screw tightness).
- Reinstall the sensor, restore the power and gas, and test a heat cycle.
If the problem persists: Have a technician check the gas pressure, burner alignment, and the IFC flame-sense circuit. Do not attempt to adjust gas pressure without proper tools and training.