Equipment error code

Trane code 2 flashes

Two flashes — pressure switch stuck open. The inducer ran but the pressure switch did not close to prove draft within the time allowed.

Equipment: furnace
Brand: Trane
Source checked: 2026-03-01

What this code means

Two flashes — pressure switch stuck open. The inducer ran but the pressure switch did not close to prove draft within the time allowed.

Source: Trane S9X1/S9V2 Service Facts — Status Light Flash Codes (18-HD64D1-1) · checked 2026-03-01

Which models show it

Trane induced-draft furnaces including XV80, XV90, S9X1, S9V2, XC80, and XC95 with standard LED diagnostics.

What is actually happening

Inducer runs, no ignition. The board waits for pressure switch closure, times out, and blinks two flashes.

Is it safe to keep running?

Heating is usually inhibited. Fix venting before forcing retries — a stuck-open switch can also mean no draft.

Shut it down when

Exhaust smell in the mechanical room, iced intake/outtake you cannot clear safely, or water pouring from the condensate assembly.

What a homeowner can safely check

Clear snow and debris from outdoor PVC intake and exhaust terminations.
Inspect pressure switch hoses for cracks or disconnects at the inducer housing.
Empty the condensate trap on 90%+ furnaces.
Listen for a grinding inducer — bearing failure reduces draft.

When to stop

Roof-line vents you cannot reach safely.
Repeated 2-flash after hoses and trap service.
Suspected heat exchanger or collector leak.

Likely causes ranked

1. Blocked or improperly sloped vent piping
How a tech confirms: Combustion analyzer and draft measurement; compares install to Trane vent tables.
Typical repair: $200–$500 · Air Conditioner Repair cost guide
2. Failed pressure switch
How a tech confirms: Vacuum test at switch ports; replacement with OEM switch.
Typical repair: $185–$400 · Air Conditioner Repair cost guide
3. Weak inducer motor
How a tech confirms: Amp draw and wheel inspection; replaces motor assembly if below spec.
Typical repair: $375–$875 · Furnace Replacement cost guide
4. Condensate blockage in collector box
How a tech confirms: Inspects collector and drain path; pressure tests secondary circuit.
Typical repair: $225–$550 · Air Conditioner Repair cost guide

Is this the end of this unit?

Major vent rework or secondary exchanger issues on older Trane units can approach replacement cost — get a written heat exchanger inspection result.

How to clear the code

After clearing vents and condensate, power cycle the furnace once. Watch for inducer start and switch click before ignition.

Why clearing is not fixing it: Two flashes return until draft is proven. A cleared code with a failed switch or motor fails again on the next call for heat.

Which trade to call

Call a licensed hvac contractor who works on furnace equipment. Gas, refrigerant, and combustion faults are not general handyman jobs.

More codes from this brand

Symptom guide: Furnace Not Heating

FAQ

What does 2 flashes mean on Trane?

Pressure switch stuck open — no draft proof during the pre-ignition window.

Can snow block cause Trane 2 flash?

Yes. High-efficiency PVC vents are sensitive to intake/exhaust blockage. Clear both pipes and retry once.

Is the pressure switch a DIY part?

Technicians replace it after proving draft. Homeowners should not jumper the switch.

Typical cost for 2-flash repair?

$185–$500 for switch or vent service; $375–$875 if the inducer motor is bad.

2 flashes vs Carrier code 31?

Same family of fault — draft proving failure — different brand labeling.

Source

Source — Trane S9X1/S9V2 Service Facts — Status Light Flash Codes (18-HD64D1-1). Checked 2026-03-01.