E3.2 1st stage pressure switch (PS1) open when it should be closed

What the control is telling you

PS1 did not close after the inducer started (S8X2 reports it after 60 seconds and speeds the inducer up to try to close it). Wind gusts can cause occasional PS1 open errors.

Applies to: Trane S8V2 (80%, 2-stage, variable speed, Link) and S8B1 / S8X1 / S8X2 (80%, 1- and 2-stage)

Likely causes

• Blocked, undersized or too-long vent
• Hose cracked, plugged or full of water
• Weak or failed inducer
• Wiring fault
• Faulty switch (least likely)

Test and repair steps

1. Confirm PS1 wiring and hose routing match the wiring diagram; in most cases the switch itself is fine.
2. Cycle power and call for 1st stage heat; measure voltage across PS1 (orange to yellow): 24 V means open, 0 V means closed.
3. Check the inducer runs; if not, measure about 120 VAC at the inducer motor leads - voltage present means a bad inducer, none means IFC or wiring.
4. Measure the draft at the switch with a manometer and compare to the set point printed on the switch label (negative pressure, compare magnitude).
5. Look for blocked or undersized vent, kinked or wet hose, then replace the switch only if draft is above the label value and it still reads open.

Settings for these units

Clearance to combustibles · Trane S8V2

24 in. front service access.

3 in. in front of the combustion air openings.

Return filter size by cabinet width · Trane S8V2

Filters are field supplied and mounted outside the cabinet.

Over 1600 CFM upflow: return on both sides, one side plus bottom, or bottom only.

• Return filter size by cabinet width · Trane S8B1, Trane S8X1, Trane S8X2

Models that show this code

37 models in Trane S8V2, Trane S8B1, Trane S8X1, Trane S8X2

Other codes on the same units

• E2.1 Ignition retries exceeded - flame never proven (1 hour lockout)
• E2.2 Flame recycles exceeded - flame lost after lighting (1 hour lockout)
• E2.3 1st stage gas valve not powered when it should be (10 times)
• E3.1 1st stage pressure switch (PS1) closed when it should be open
• E3.3 2nd stage pressure switch (PS2) closed when it should be open
• E3.4 2nd stage pressure switch (PS2) open when it should be closed
• E04 Open limit (main limit, rollout or reverse airflow)
• E4.0 Main high limit open