1 red flash
Flame sensed when there is no call for heat
This code typically points to
- Leaking or slow-closing gas valve
- Shorted or contaminated flame-sense path
- Faulty control board
Next checks to confirm
- Verify no call for heat and gas valve should be closed
- Inspect flame-sense circuit for shorts/contamination
- Verify valve leakage or slow-close
Escalation
Leaking gas valve is a safety concern. If no external cause, gas valve or control fault becomes likely.
Reset behavior
Clears when condition is removed.
Safety Critical
Immediate concern