Trane furnace E3.3: Meaning & Fix

Status codeE3.3Trane

What does Trane E3.3 mean?

2nd stage pressure switch PS2 is closed when it should be open. The service facts say the pressure switch is not the problem in most cases.

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How it shows: 7-segment display on a Trane S9V2 two-stage variable-speed furnace (Service Facts S9V2-SF-2A-EN): E3.3

Likely causes

PS2 wiring or tube routing is not correct
PS2 is not oriented for the application
The switch itself, after the orientation and wiring checks

Safe checks for E3.3

Do not jumper PS2. The note on this chart says 24 volts across the switch means it is open, and 0 volts means it is closed
Techniciancycle power off and on, confirm PS2 orientation against the installer's guide, and measure across PS2 (brown to yellow). The chart says to replace the pressure switch when that voltage is not present, and to verify the wiring or replace the IFC when 24 volts is present

Safety firstIf you smell gas, do not touch any electrical switch or use a phone in the building; leave immediately and call your gas supplier from outside. Turn off electrical power at the furnace switch or breaker before opening any panel, and never bypass or jumper a limit, rollout or pressure switch. Gas valve, burner, venting, wiring and control-board work should be done by a licensed HVAC technician.

Capacitors can hold a charge after the power is off. Safety terms.

When to call a pro

Call a licensed HVAC technician. E3.3 is PS2 stuck closed. E3.1 is the 1st stage switch. E3.4 is PS2 open when it should be closed.

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Parts & tools for this fix

Taken from this code's causes or steps. A search link opens Amazon results and does not confirm a fit. Check the model number in the manual.

Furnace pressure switch: guide

Technician step in this code: cycle power off and on, confirm PS2 orientation against the installer's guide, and measure across PS2 (brown to yellow). The chart says to replace the pressure switch…

This one is for a technician to test or replace, so we only explain it and do not link to buy it.

Multimeter for appliance and HVAC diagnosis: guide

In this code: Do not jumper PS2. The note on this chart says 24 volts across the switch means it is open, and 0 volts means it is closed