Trane Furnace: 6 Flashes
Code 6 Flashes: The 115 volt AC line and neutral are reversed at the furnace, or the furnace is poorly grounded
WarningShown as: 6 flashes, pause, repeat
The 115 volt AC line and neutral are reversed at the furnace, or the furnace is poorly grounded. The control needs correct polarity and a good ground to sense flame.
Manual wording: “6 Flashes --- 115 Volt AC power reversed or Poor Grounding”
Documented for: *UH1 / *DH1 condensing furnaces (XR 95 family) and other Trane furnaces using the LED-only integrated furnace control
Likely causes, most common first
- 115 Volt AC power reversed
- Poor grounding
What you can safely check yourself
- Note whether the code appeared right after electrical work, a new outlet, or a generator was used
When to call a technician
Call a technician or electrician. Correcting line polarity and grounding is electrical work inside the furnace and the panel.
A Trane furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Installer's Guide - Upflow/Horizontal, Downflow/Horizontal, Gas-Fired, Direct Vent Condensing Furnaces (18-CD29D1-14-EN) (Trane, *UH1B/*UH1C/*UH1D upflow and *DH1B/*DH1C/*DH1D downflow condensing gas furnaces (XR 95 family; first letter A or T)) · checked 2026-08-25