Rheem R802VA07542117MSA Error Code A127_F: Flame Present with Gas Valve Off - UL
What Does Code A127_F Mean?
Fault code A127_F on the Rheem R802VA is a UL (Underwriters Laboratories) safety fault similar to A014_F, but specifically classified as a UL compliance safety alarm. It occurs when the flame sensor detects flame presence while the IFC has confirmed the gas valve relay is open (valve should be off). This indicates that either the gas valve is stuck open and continuing to supply gas, or the flame sensor circuit is producing a false positive signal.
The UL designation makes A127_F a higher-severity classification than A014_F even though both detect the same physical condition of undesired flame. UL safety faults are directly tied to the safety certifications that allow the furnace to be legally installed and operated in the United States. When a UL fault is active, the furnace has violated a certified safe operating condition.
A gas valve stuck in the open position is the primary safety concern. If the valve cannot be confirmed closed, gas will continue to flow even when the furnace is in a lockout state, creating a combustion or carbon monoxide risk. The control board relay may also have failed in a welded-closed state, keeping voltage applied to the gas valve regardless of the IFC command.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Gas valve stuck in open position | Most common | ✗ Call a pro → |
| Faulty flame sensing circuit giving false positive | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Turn off the manual gas supply valve immediately and call a technician — do not restart the furnace
- A technician must verify that the gas valve closes fully when commanded off before any attempt to restart the furnace
- If the control board gas valve relay is welded, the board must be replaced before the furnace is operated again
✓ Verified against manufacturer service manual — March 2026