E3.3 2nd stage pressure switch (PS2) closed when it should be open

What the control is telling you

PS2 reads closed before 2nd stage was called. Usually wiring or tube routing rather than the switch.

Applies to: Trane S8V2 and S8X2 (2-stage models with PS2)

Likely causes

• Incorrect PS2 wiring or hose
• PS2 mounted in the wrong orientation for the furnace position
• Stuck switch

Test and repair steps

1. Check PS2 wiring and hose routing.
2. Make sure PS2 is rotated correctly for the installed orientation (see the combustion air conversion section).
3. Cycle power off and on, then measure across PS2 (brown to yellow) with the inducer on low: 0 V means closed.
4. If PS2 reads closed at low inducer speed, replace the switch.

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

19 models in Trane S8V2, Trane S8X2

Other codes on the same units

• 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
• E3.2 1st stage pressure switch (PS1) open when it should be closed
• 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
• E4.1 Reverse airflow limit open