E4
Flame sensed with no call for heat
This code typically points to
- Short to ground in flame-sense circuit
- Lingering burner flame
- Slow-closing gas valve
Next checks to confirm
- Correct short at flame sensor/flame-sensor wiring
- Check for lingering flame
- Verify proper gas-valve operation
Escalation
Induced-draft blower and circulator blower run continuously; no furnace operation
Reset behavior
Clears after false-flame condition is removed.
Safety Critical
Immediate concern