York TM9E furnace 9 red flashes: Polarity or Ground Fault
Professional repair
What do 9 red LED flashes mean on a York TM9E furnace? The control has detected reversed line-voltage polarity, a grounding problem, or reversed low-voltage transformer wires. Heating and cooling are both affected, and ignition is blocked until it is corrected.
Before you touch anything: the six signs that mean stop troubleshooting and call a pro →
Polarity, grounding, transformer wiring and flame-probe circuit checks involve live electrical testing. A qualified technician should make these measurements and any wiring corrections.
Possible causes
- Reversed line-voltage polarity at the furnace supply TECH
- Poor grounding, including the flame-probe electrical path TECH
- Transformer low-voltage leads connected in reverse TECH
Parts for this code
No model-verified part number is listed here. Have the fault diagnosed and the correct part matched to your furnace before ordering.
Questions about this code
What do 9 red LED flashes mean on a York TM9E furnace?
The control has detected reversed line-voltage polarity, a grounding problem, or reversed low-voltage transformer wires. Heating and cooling are both affected, and ignition is blocked until it is corrected.
How do I fix York TM9E furnace 9 red flashes?
Book electrical diagnosis and mention any recent electrical, thermostat or furnace wiring work, which can help narrow the cause. Leave the wiring alone; the technician identifies which of the three conditions applies and corrects it.
How much does it cost to fix York TM9E furnace 9 red flashes?
The cost is driven by diagnostic and electrical labor. It depends on whether the fault is in the furnace wiring, the transformer connections or the building supply.
Applies to
TM9E
Different York generations use different code maps. If your series isn't listed, don't assume this meaning — check your blower-door label.
Verified against YORK TM9E Series Installation Manual — Single Stage ECM Residential Gas Furnaces, p.34
Last verified 2026-10-07 · page updated 2026-10-07 · how we verify
Related York furnace codes
These codes use the same york tm9e single-stage ecm tri-color led control system.