York TM9V080B12MP11 Error Code 2 Red Flashes: Pressure Switch Stuck Closed
What Does Code 2 Red Flashes Mean?
At the very beginning of each heat cycle — before the inducer has built any draft — the pressure switch contacts should be open. This York board deliberately verifies that open state as a self-check: if the contacts are already closed when there is no inducer draft to close them, the board cannot trust the switch to prove venting later in the cycle, so it refuses to start the ignition sequence at all. The furnace will not heat until the fault clears.
A pressure switch whose contacts have stuck closed is the most common cause. After thousands of cycles the switch's diaphragm and contacts can weld or stick in the closed position. Miswiring is the other listed cause, and it shows up most often right after a service visit or switch replacement, where a jumpered or crossed connection makes the board read the switch as permanently closed.
This is the opposite condition to the 3 Red Flashes code, where the pressure switch is open when it should be closed. Two flashes means the board never saw the expected open state at rest; three flashes means the board never saw the expected closed state once the inducer was running.
What You'll Notice
- The furnace does not begin its ignition sequence and produces no heat.
- The fault is flagged right at the start of a call for heat, before ignition would normally occur.
- The condition frequently appears soon after a recent pressure-switch replacement or other furnace service (a wiring clue).
- The inducer may not proceed through its normal pre-purge because the board has halted the sequence.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Faulty pressure switch stuck in closed position | Most common | ✗ Call a pro → |
| Miswiring of pressure switch | Common | ✗ Call a pro → |
How This Is Diagnosed
A technician verifies the pressure switch is actually open at rest by metering its contacts with the inducer off; a switch that reads closed with no draft confirms stuck contacts and is replaced. If the switch itself checks out, they inspect the wiring for a short, a jumper left in place, or a crossed connection that would make the board see a closed circuit — the common finding when the code appears after recent service. The pressure switch is a safety device and is never bypassed to force the furnace to run.
When to Call a Professional
This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:
- The code appears and the furnace will not start its ignition sequence.
- The problem started right after a pressure switch was replaced or the furnace was serviced.
- The code clears and returns intermittently, suggesting a marginal switch or loose connection.
Frequently Asked Questions
What does 'pressure switch closed when it should be open' actually mean?
Before the inducer runs, the switch should read open. If the board sees it already closed at rest, it cannot trust the switch to verify venting later, so it blocks ignition. That usually means a stuck switch or a wiring fault.
Can a stuck pressure switch be reset?
No. A switch stuck closed needs to be tested and, if confirmed faulty, replaced by a technician. It should never be bypassed, because it is a venting safety device.
Why did this start right after my furnace was serviced?
Miswiring is a listed cause of this code, and a crossed or jumpered pressure-switch connection made during service can make the board read the switch as closed. A technician can check the wiring.
✓ Verified against manufacturer service manual — March 2026