York 2 Flashes Error Code — What It Means
Two flashes on a York furnace diagnostic LED indicates the pressure switch is stuck in the closed position when it should be open. At the beginning of a heat cycle, the control board checks that the pressure switch is open (meaning no draft is present) before starting the induced draft motor. If the switch reads closed before the inducer starts, the board interprets this as a stuck or shorted switch and locks out the ignition sequence.
Common Causes
- Pressure switch contacts welded closed — Electrical arcing over time can fuse the switch contacts in the closed position.
- Water in the pressure switch hose or switch body — Condensate from the flue can back up into the rubber hose and into the switch, holding the diaphragm in the closed position.
- Miswired pressure switch — An incorrectly wired switch (normally-closed port used instead of normally-open) can appear stuck closed at startup.
- Inducer running when it shouldn’t — A board with a stuck inducer relay may keep the inducer running, which closes the pressure switch before the board’s startup check.
Step-by-Step Fix
- Disconnect power and inspect the pressure switch hose — Remove the rubber hose from the switch port and drain any visible water. Blow through the hose to confirm it is clear.
- Test the pressure switch with a multimeter — With the furnace off and the inducer not running, check continuity across the pressure switch. If it reads closed (continuity), the switch is stuck — replace it.
- Check for water in the condensate trap (90+ AFUE furnaces) — On high-efficiency furnaces, a blocked condensate trap can push water back into the inducer and up the pressure hose. Clear the trap and drain the hose.
- Inspect control board for stuck inducer relay — If the inducer is running with no heat call and no power cycle change, the board relay may be stuck. Replace the board.
- Reset and confirm — Restore power and watch the startup sequence. The pressure switch LED indicator (if equipped) should be off at startup; it closes only after the inducer reaches speed.
Parts Often Needed
| Part | Notes |
|---|---|
| Pressure switch | Match York/Johnson Controls part number exactly |
| Pressure switch hose | 1/4” ID; replace if water-logged or cracked |
| Condensate trap kit | Required if condensate is backing up |
| Control board | Replace only if relay is confirmed stuck |
Technician Tips
Modern furnaces use LED flash codes on the control board to diagnose failures. Before calling for service, count the number of flashes between pauses and check your owner’s manual for the code chart. The most common furnace error — 1-4 flashes usually means ignition failure — is often caused by a dirty flame sensor. The flame sensor is a $15-30 part that takes 10 minutes to clean. Remove it with a 1/4” nut driver, gently scrub the metal rod with emery cloth or a dollar bill (yes, a dollar bill — it’s the right abrasiveness), and reinstall. This fixes about 60% of “no heat” service calls.
DIY vs Pro: Error codes related to pressure switches (usually 2-3 flashes) often indicate blocked vents or condensate drains — safe to check yourself. Codes related to gas valves or ignition modules (4+ flashes) are best left to a licensed HVAC technician.
Need Replacement Parts?
Finding the right replacement parts for your equipment is critical to getting it running again. Check current prices on Amazon — prices and availability change frequently.
When to Call a Pro
If water contamination is recurring, the condensate drainage system needs a thorough inspection by a licensed HVAC technician to prevent repeated lockouts and potential heat exchanger corrosion.