American Standard · Furnace / HVAC
5 flashes Flame sensed with gas valve off
What this code means
The board detects a flame signal when the gas valve should be closed — a hard safety lockout.
Most likely causes
- Gas valve stuck partially open
- Faulty flame sensor giving a false reading
What to try first
Do not attempt to bypass this fault. Shut off gas to the unit and don't keep resetting it.
Safety first: stop using the appliance and shut off its gas or power until it has been inspected — this fault category is associated with fire or gas risk.
FAQ
What does American Standard error code 5 flashes mean?
Flame sensed with gas valve off. The board detects a flame signal when the gas valve should be closed — a hard safety lockout.
Can I fix American Standard code 5 flashes myself?
No — stop using the appliance and shut off its gas or power until it has been inspected. This fault category is associated with fire or gas risk.
What causes American Standard code 5 flashes?
The most common causes are: gas valve stuck partially open; faulty flame sensor giving a false reading.
Other American Standard furnace codes
All American Standard furnace error codes →
Other furnace brands: Trane · Carrier · Lennox · Goodman · Amana · Rheem · Bryant · Generic · Nest
This information may contain errors or not apply to your exact model — always double-check it against your appliance's own manual before acting. If there's any chance of a gas, fire, electrical, carbon monoxide, or other safety hazard, stop and call a licensed professional or the appropriate agency (e.g. your gas utility) instead of relying on this page alone.