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TM9X/TM9E - Diagnostic Codes

Article ID: 578
Last updated: 1 Dec, 2018

York Gas Furnaces: TM9X/TM9E

Re: Diagnostic Codes / Fault Codes

These York gas furnaces have a control board inside the furnace blower compartment that will flash a diagnostic code that shows the operating status of the furnace.

Diagnostic Codes:
Slow Green Normal Operation - no call for heat
Slow Amber Normal Operation - with a call for HEATING
4 Amber No Call for G.
  • Check low voltage wiring
Steady On Control fault has been detected or there is 24 volts present without 115 volts.
  • Check that there is 24 volts and 115 volts being supplied to the board. If so, then the board should be replaced.
1 Red Flame present with gas off
  • Stuck gas valve
  • Shorted flame sensor 
  • Faulty control
2 Red Pressure switch stuck closed
  • Bad pressure switch
  • Inducer fan relay stuck on
3 Red Pressure switch stuck open
  • Bad pressure switch
  • Bad inducer fan
  • Bad inducer fan relay
  • Blocked or restricted vent
  • Condensate drainage issue
4 Red Limit switch open / open fuse
  • Bad limit
  • Low airflow
  • Over-Fired
5 Red Rollout switch open / open fuse
  • Bad switch
  • Cracked heat exchanger
  • Bad inducer motor
  • Over-Fired
6 Red

Multiple Code 3's

  • Bad pressure switch
  • Bad inducer fan
  • Bad inducer fan relay
  • Blocked or restricted vent
  • Condensate drainage issue
7 Red Ignition lockout due to 3 retries
  • Bad igniter
  • Dirty flame sensor
  • No gas flow
8 Red Flame signal lost 5 times
  • Dirty flame sensor
  • Combustion air problem
9 Red Grounding or line polarity fault
  • Try reversing transformer power
10 Red Gas valve circuit shorted
  • Check gas valve wiring
11 Red Extended limit switch open
  • Bad limit
  • Blower failure

Fault Code Retrieval:  With no thermostat call push and release the LAST ERROR button.  The LED will flash up to 5 stored fault codes, beginning with the most recent.  If there are no codes in memory, the LED will flash two green flashes.

Clear the Fault Codes:  Push and hold the LAST ERROR button for at least five seconds.  The LED will flash three green flashes when the memory has been cleared.

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Article ID: 578
Last updated: 1 Dec, 2018
Revision: 3
Access: Public
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