Trane TUH1B080A9H31A Error Code 6 Flashes: 115V AC Power Reversed or Poor Grounding
What Does Code 6 Flashes Mean?
A 6-flash code on the Trane TUH1B080A9H31A means the control board has identified an electrical wiring problem. Either the 115VAC hot and neutral wires are swapped, or the furnace ground connection is insufficient. Both conditions compromise the flame sensing circuit, which needs correct polarity and grounding to accurately detect the burner flame.
Reversed polarity is the most frequent cause, typically resulting from incorrect wiring during initial installation or after electrical work in the home. Poor grounding develops over time as wire connections oxidize or become loose, especially in humid environments. The furnace may intermittently operate with either condition, but flame detection will be unreliable, causing unpredictable shutdowns during heating cycles.
This is an electrical wiring issue that requires a licensed HVAC technician or electrician. The repair involves verifying polarity at the furnace's electrical connection with a multimeter and ensuring the ground wire has a solid, low-resistance path to the electrical panel ground. Once corrected, the furnace should operate reliably.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Reversed hot and neutral wiring | Most common | ✗ Call a pro → |
| Poor or missing ground connection | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- When this code appears — correcting wiring polarity and grounding requires a qualified technician or electrician
✓ Verified against manufacturer service manual — March 2026