TUH2/TDH2 - Diagnostic Codes

Article ID: 748
Last updated: 10 Apr, 2024

Trane Gas Furnaces: TUH2/TDH2

Re: Furnace Lockout Codes / Diagnostic Codes

Flashing Slow Normal - No call for heat
Flashing Fast Normal - Call for heat
On Replace Control
Off Check Power
2 Flashes Lockout due to re-tries or recycles
3 Flashes Pressure switch fault (open or closed)
4 Flashes Open limit circuit
5 Flashes Flame sensed with no call for heat
6 Flashes Reversed polarity, low voltage or poor ground
7 Flashes Gas valve circuit error
8 Flashes Low flame signal
9 Flashes Check Ignitor, Possible grounding problem


On power up, the last 4 faults, if any, will be flashed on the Red LED.

  • The newest fault detected will flash first and the oldest last.
  • There will be a 2 second delay between fault code flashes.
  • Solid Red LED error codes will not be displayed.
  • The Green LED will be on solid during last fault recovery.  At any other time the control is powered, the Green LED indicator light will operate as shown in the table above and the Red LED will flash LitePort data (one flash) every 20 seconds.

​​​​​​​Fault Code Reset

The last 4 fault codes can be erased from memory by powering up the control with “G” energized and then applying “R” to the “W1” terminal 3 times within 6 seconds.

  • The control will acknowledge the reset by turning on the red LED for 2 seconds.

This article was:   Helpful | Not helpful
Report an issue
Article ID: 748
Last updated: 10 Apr, 2024
Revision: 5
Access: Public
Views: 194
Comments: 0