Trane Furnace 5 Flashes
Safety faultShown as: 5 flashes, pause, repeat
Flame is being detected when there should be no flame present. The control sees a flame signal with the gas valve commanded off.
Manual wording: “5 Flashes --- Flame sensed when no flame should be present”
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
- Flame sensed when no flame should be present
- Gas valve leaking through or slow to close
- Faulty flame sensing circuit
What you can safely check yourself
- Turn the furnace switch off and leave it off
- If you smell gas, leave the house and call the gas utility from outside
When to call a technician
Call a technician. A false or lingering flame signal points at the gas valve or flame-proving circuit and is not a homeowner repair.
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