Goodman GMSS960803BN Error Code 5 Flashes: Flame Sensed With No Call for Heat
What Does Code 5 Flashes Mean?
Five flashes on the Goodman GMSS960803BN diagnostic LED indicate that the control module is sensing flame when the thermostat is not calling for heat. The furnace locks out heating operation and runs both the inducer and circulator blowers continuously as a safety measure.
The flame sensor on this furnace works by passing a microamp-level current through the gas flame. If the control module reads flame current when the gas valve should be closed, it indicates a fault in the flame sensing circuit. The most common cause is a short to ground in the flame sensor wiring — a damaged or chafed wire that touches the furnace chassis can create a false flame signal.
A flame sensor rod that is physically touching a grounded metal surface will also produce this code. The rod must be electrically isolated from the furnace frame by its ceramic insulator. If the insulator is cracked or the rod has shifted out of position, contact with grounded metal creates a conductive path that mimics a flame signal.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Short to ground in flame sensor wiring | Most common | ✗ Call a pro → |
| Faulty flame sensor rod touching ground | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- The furnace shows 5 flashes with both blowers running continuously
- There is no visible flame in the burner area
- The flame sensor or its wiring appears damaged
✓ Verified against manufacturer service manual — March 2026