American Standard AUH1B080A9H31A Error Code 6 Flashes: 115V AC Power Reversed or Poor Grounding
What Does Code 6 Flashes Mean?
Code 6 (6 Flashes) on the American Standard AUH1B080A9H31A indicates that the 115V AC line and neutral wires are reversed or the furnace has an inadequate electrical ground. Correct polarity and grounding are essential for the flame sensing circuit to function properly — without them, the furnace may fail to detect flame or detect false flame signals.
Reversed polarity is the most common trigger for this code. It typically occurs after the furnace has been installed, a control board has been replaced, or electrical work has been done in the home. The hot wire and neutral wire are connected to the wrong terminals at the furnace junction box. This is a straightforward fix for a qualified person, but the power must be completely off before any wiring changes.
A poor or missing ground connection is the second possible cause. The furnace must be properly bonded to the home's grounding system for safe operation. The furnace may still run intermittently with this code, but the flame sensing system will not be reliable, potentially creating safety issues. Have an electrician or HVAC technician verify the wiring polarity and ground connection.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Reversed hot and neutral wires at furnace connection | 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:
- The LED shows 6 flashes — an electrician or HVAC technician should check the wiring polarity and ground connection
- The furnace operates unreliably or shows intermittent flame sensor errors along with this code
✓ Verified against manufacturer service manual — March 2026