York furnace 2 red flashes: Pressure switch stuck closed, or an inducer error
Two red flashes means the pressure switch was closed when it should have been open, or the control has found an inducer problem. The switch must sit open at rest.
Applies to: York, Luxaire and Coleman gas furnaces using the UTEC or W/R integrated furnace control boards documented in technical service letter ST-045-09. Stored in the error code array.
What it means
The pressure switch proves the inducer is moving air before gas is released, and at rest it must be open. The control verifies that before every cycle, because a switch stuck closed would prove a draft that does not exist — allowing the furnace to fire into a flue that could be blocked. York's later boards pair this with an inducer error at the same flash count, which is a sensible grouping: both mean the draft-proving chain cannot be trusted, though they sit at different points in it.
Most common causes
- Pressure switch contacts stuck or welded closed.
- The sensing hose pinched or kinked so that it traps pressure.
- Water in the sensing hose or the pressure tap holding the switch closed.
- A short in the pressure switch wiring, electrically indistinguishable from closed contacts.
- An inducer fault the control has detected separately.
- The wrong pressure switch fitted at a previous repair.
- The low and high stage switches swapped during service.
How to diagnose it
- Note whether the inducer starts at all, since the control usually stops before that step on this fault.
- Note whether the furnace was serviced recently, since a hose or switch disturbed during other work is a common trigger.
- Check the condensate drain for backing up, since water reaching the sensing hose is a frequent cause.
- Have the stored fault history replayed, since this code is retained in the error array.
How to fix it
- Clearing a blocked condensate drain is reasonable homeowner work and addresses one of the causes.
- The pressure switch, its hoses, its wiring, and the inducer are technician work.
- Never jumper a pressure switch to get heat. It is the only thing between a blocked flue and a firing burner.
- Replace a failed switch with the exact part for the model, since setpoints are model-specific.
Notes
This code and the three-flash code are opposite halves of the same test. Counting accurately matters more here than almost anywhere else in the set, because the two point at opposite conditions and different repairs.