What do York furnace error codes mean?
On the York TM9E, slow green or amber flashing is normal; 2 and 3 red are pressure switch faults, 4 red an open limit and 5 red an open rollout. Other models differ, so use your chart.
Key points
- On the York TM9E, a slow green flash means normal standby and a slow amber flash means normal heating; red flashes are faults.
- The table comes from Johnson Controls' TM9E installation manual (form 6019630-UIM-F-0423). Other York models and board revisions can differ.
- Count the flashes through the door window without removing panels, and write the number down before anyone cycles the power.
- Common families are pressure switch (2, 3, 6), limit (4, 11), rollout (5) and ignition or flame (7, 8).
- Reset once at most. Open limit, rollout and gas valve codes are stop-and-call.
On a York TM9E furnace, slow green or amber flashing is normal, and red flashes are a fault count: 2 and 3 red are pressure switch faults, 4 red is an open limit and 5 red is an open rollout. Look through the door window, watch for the pause between patterns and count the red flashes first. The codes below come from one York manual and one model family, so compare them with the chart on your own furnace door.
Which York manual are these codes from?
The table is from Johnson Controls' installation manual for the York TM9E series, a single-stage ECM 95% AFUE multi-position gas furnace (form 6019630-UIM-F-0423, section on normal operation and diagnostics). Codes can differ by control board and series, and they can change between models and board revisions; the chart on your furnace door is the final word.
Our York brand page covers the York furnaces we service.
How to read the York LED safely
- Look through the window in the door. Don't take panels off or reach into the blower or burner compartment with power on.
- Know the timing. The manual says slow flashes are 2 seconds on and 2 seconds off. Fault codes flash 1/3 second on and 1/3 second off, once per count, then a 2-second pause before the pattern repeats.
- Count more than once. A pattern like six flashes, pause, six flashes is a code. Count three cycles to be sure.
- Write down the color and number, then photograph the rating plate for the model number.
- Read it before anyone cycles the power. A power cycle can clear what you needed to see.
TM9E LED codes
| LED pattern | Meaning in the TM9E manual |
|---|---|
| Slow green flash | Normal operation, no thermostat call |
| Slow amber flash | Normal operation with a call for heat |
| Off | No flashing: check for power to the board and a blown board fuse |
| Steady, any color | Control failure |
| 1 red | Flame sensed when there was no call for heat |
| 2 red | Pressure switch closed when it should be open |
| 3 red | Pressure switch open when it should be closed |
| 4 red | Main limit switch open |
| 5 red | Rollout switch open (manual reset) |
| 6 red | Pressure switch opened four times in one call for heat; one-hour lockout |
| 7 red | No flame established in three ignition trials; one-hour lockout |
| 8 red | Flame lost five times in a call for heat; one-hour lockout |
| 9 red | Reversed line polarity, grounding problem or reversed transformer wires |
| 10 red | Gas valve energized with no call for heat |
| 11 red | Main limit open for more than 5 minutes; hard lockout |
| 4 amber | Y signal from the thermostat without a G signal (wiring alert) |
What the common code families mean
Pressure switch (2, 3, 6). The furnace proves the inducer is venting before it lights. The manual lists a faulty inducer, blocked vent pipe, broken hose and a bad switch among the causes. In Minnesota the first place we look is frost or snow over the PVC vent terminations. Our pressure switch guide and inducer motor guide go deeper.
Limit (4, 11). The furnace overheated. The manual lists a dirty filter, wrong duct sizing, wrong blower speed, wrong firing rate, loose wiring or a faulty blower motor. Eleven red adds a failed blower motor or wheel.
Ignition and flame (7, 8). The manual lists low gas pressure, a dirty or faulty flame sensor, a faulty ignitor or a gas valve switch left off. The furnace tries again after an hour.
Rollout (5) and gas valve (1, 10). These are safety conditions. The manual says a rollout trip needs a check of combustion air, inducer operation, the heat exchanger and the burners.
Wiring (9, 4 amber). Nine red is a polarity or grounding fault and the furnace won't start until it's fixed. Four amber is only a thermostat wiring alert; the manual says heating and cooling still work.
Safe checks before you call
Run the basic checks in our general furnace light codes guide: thermostat, switch and breaker, filter, snow on the PVC vents and water at the furnace. Then cycle power once and watch. If the same code returns, stop. Never jump a pressure, limit or rollout switch, and never press the reset or LAST ERROR button repeatedly to keep it running. A gas smell means getting out of the house first, then calling your gas utility or 911 from outside.
When to call us
When you call, tell us the color and the count, for example 7 red or slow amber, and the model number from the rating plate. The three one-hour lockouts (6, 7 and 8 red) share a retry timer but point at different parts: 6 is the pressure switch circuit, 7 is ignition and 8 is flame stability, so the number saves a step on the visit. Call if a code comes back after one reset, or for any of 1, 5, 9, 10 or 11 red. With us, a furnace repair visit is a $79 trip charge, waived when you approve the repair, with a written flat-rate price first. See furnace repair in Minneapolis. Call 612-429-3465 any day from 7am to 9pm with the red flash count and the model number ready.
Common questions about heating
What does a slow green flash on a York furnace mean?
On the TM9E, a slow green flash is normal operation with no thermostat call, and a slow amber flash is normal operation with a call for heat. The manual defines slow as 2 seconds on and 2 seconds off. If the light never flashes, check for power to the board and a blown board fuse before assuming the control has failed.
What does 3 red flashes mean on a York furnace?
On the TM9E, 3 red flashes mean the pressure switch contacts are open when they should be closed. The manual points to a faulty inducer, blocked vent pipe, broken pressure switch hose, a disconnected switch or inducer wire, or a bad switch. In winter, check that the outside PVC vents are clear of snow and frost.
Do York, Coleman and Luxaire furnaces use the same codes?
Coleman and Luxaire are also Johnson Controls brands, but codes depend on the model and board, even within York. Use the chart on the inside of your own furnace door or in its manual, and call us with the model number if you are unsure.
Can I use the LAST ERROR button on my York furnace?
The TM9E manual describes a LAST ERROR button that replays up to five stored codes, and says it must only be used by a qualified service technician. Holding it for more than 5 seconds clears the memory, which also erases history we use for diagnosis. Leave it alone and tell us the code you saw.