Trane furnace E3.2: Open pressure switch, first stage
E3.2 means the first stage pressure switch did not close. The inducer is running but the control never got proof that the flue is clear, so it will not light the burners.
Applies to: Trane and American Standard S9V2 two-stage condensing variable speed gas furnaces with a seven-segment integrated furnace control display, per Installer's Guide 18-CE01D1-1E-EN.
What it means
This control treats the two firing stages separately and gives each its own pressure switch code, which is more precise than most. E3.2 is the first stage switch failing to close. In Trane's own sequence of operation the control energises the first stage inducer and waits for PS1 to close before it will close the igniter relay — so nothing downstream of that point happens. That is why the furnace sits with the inducer running and never glows. The switch is the interlock that proves the vent is clear and the inducer is moving air, and until it closes the control has no evidence it is safe to admit gas.
Most common causes
- A blocked vent or intake termination outside — snow, ice, a nest, or a cap left on.
- Water in the pressure switch hose, the collector box, or a blocked condensate drain.
- A cracked, kinked or disconnected hose.
- An inducer running but not developing enough suction, from bearing wear or a dirty wheel.
- A failed pressure switch, or one of the wrong specification fitted previously.
How to diagnose it
- Check the vent and intake terminations outside. Homeowner work, and a large share of these in cold weather.
- Note whether the inducer sounds normal, weak or noisy.
- Note any standing water near the furnace, which points at the condensate path.
- Check the Last 6 Faults menu — a stored E09 alongside this points at the condensate side rather than the vent.
How to fix it
- Clear the vent or intake termination if blocked.
- Everything inside the cabinet is technician work.
- Never jumper a pressure switch to force the furnace to run. It is the interlock that stops it burning gas with a blocked flue.
Notes
Trane pairs each stage's open condition with a shorted condition — E3.1 is a shorted first stage switch, E3.2 open, E3.3 shorted second stage, E3.4 open second stage. That symmetry makes the table easy to read once you know it exists.
Related
All codes for this manufacturer
Trane and American Standard furnace flash codes — every code, with what differs between models.