Kelvinator furnace shows E4 and burners do not light

Safety first: Turn OFF electrical power and shut off the gas valve before working near the burner compartment. Allow the furnace to cool.

• Verify gas supply: Ensure the manual gas shutoff valve near the furnace is parallel to the pipe (open). Check that other gas appliances in the home operate normally.
• Inspect hot surface ignitor: Locate the ignitor near the first burner. Do not touch the element with bare fingers. Look for cracks, white spots, or breaks in the ceramic or silicon carbide element. Replace if damaged.
• Clean flame sensor: Remove the flame sensor (usually a single rod in front of a burner) with a small nut driver. Gently clean the rod with fine steel wool or emery cloth until shiny. Reinstall and tighten the screw.
• Check wiring to gas valve: Confirm the two wires to the gas valve are firmly connected and not burned or pinched.
• Restart furnace: Restore power and gas, then call for heat. Watch through the sight glass: inducer starts, ignitor glows, then gas should flow and burners light. If the ignitor glows but no flame appears, the gas valve or gas supply may be at fault and requires professional service.