Goodman GMSS920803BN Error Code 5 Flashes: Flame Sensed With No Call for Heat
What Does Code 5 Flashes Mean?
Five flashes on the Goodman GMSS920803BN diagnostic LED indicate that the control module is sensing flame when no call for heat is active. As a safety response, both the inducer and circulation blowers run continuously while the furnace is otherwise locked out from heating operation.
This condition is almost always caused by a short to ground in the flame sensor circuit. The flame sensor works by detecting a tiny electrical current that passes through the burner flame. If the sensor wire is damaged, touching the furnace chassis, or if the sensor rod itself is grounding out against the burner assembly, the control module receives a false flame signal.
A faulty flame sensor rod that is touching ground can also produce this code. The rod must be electrically isolated from the furnace body to function correctly. If the ceramic insulator is cracked or the rod has shifted position, it can make contact with a grounded surface and create a false flame reading.
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 and both blowers run continuously
- You see no visible flame in the combustion chamber
- The flame sensor wire appears damaged or touching the furnace body
✓ Verified against manufacturer service manual — March 2026