York TM9E furnace 3 red flashes: Pressure Switch Open
Professional repair
What do 3 red LED flashes mean on a York TM9E furnace? The control expected the pressure switch to be closed and found it open. York lists several checks for this, so the code alone does not prove a failed switch.
This condition involves the gas or combustion side. If you smell gas or a CO alarm sounds: leave, then call your gas utility. Diagnostic info here is reference — combustion repairs are for licensed technicians. All six emergency signs →
Safe checks before calling
From the ground, look at the outdoor intake and exhaust terminations for snow, ice or debris. Report any blockage to your technician and do not disassemble the venting.
A technician checks the inducer, venting, pressure hose, switch and wiring in turn. Adjusting or bypassing the pressure switch is never an acceptable fix.
Possible causes
- Blocked vent, which may show at the outdoor termination DIY-CHECKABLE
- Inducer fault or damaged pressure hose TECH
- Disconnected switch or inducer wires, or a switch fault 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 3 red LED flashes mean on a York TM9E furnace?
The control expected the pressure switch to be closed and found it open. York lists several checks for this, so the code alone does not prove a failed switch.
How do I fix York TM9E furnace 3 red flashes?
After the outside look, book service with the LED color, count and anything you saw at the terminations. The technician works through the inducer, vent, hose and wiring before replacing the switch, since several causes produce this same code.
How much does it cost to fix York TM9E furnace 3 red flashes?
Cost varies with the finding: a reconnected wire or hose is mostly labor, while an inducer or switch replacement adds parts. Vent repairs depend on the venting layout.
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.33
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.