Trane Error Code E3.4: 2nd stage pressure switch (PS2) open when it should be closed (Furnace)
Trane error code E3.4 on a furnace means: 2nd stage pressure switch (PS2) open when it should be closed. It is also called Trane diagnostic code E3.4.
Homeowner? What Trane code E3.4 means for you
Check, then call Your furnace is reporting: 2nd stage pressure switch (PS2) open when it should be closed. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.
Safe things you can check yourself
- Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
- Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.
- Make sure the furnace front door or panel is closed properly; many furnaces will not run with the door switch open.
- Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
- Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
- Check that the gas valve next to the furnace is open (handle in line with the pipe). Do not force it.
- Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does Trane error code E3.4 mean?
PS2 did not prove on a 2nd stage call (S8X2 allows 45 seconds). The furnace drops to 1st stage, retries after 10 minutes, and after the third failure in the same call stays on 1st stage.
Applies to: Trane S8V2 and S8X2 (2-stage models with PS2)
Common causes of Trane code E3.4
- Vent restriction or wrong vent size
- PS2 hose problem
- Inducer not reaching high speed
A technician checks these and 1 other possible causes on site before replacing any part.
Trane models that use code E3.4
S8V2A040M3PCBS8V2A040M3PDS8V2B060M4PCBS8V2B060M4PDS8V2B080M4PCBS8V2B080M4PDS8V2C080M5PCBS8V2C080M5PDS8V2C100M5PCBS8V2C100M5PDS8V2D120M5PCBS8V2D120M5PDS8X2A040M3PSABS8X2B060M3PSABS8X2B060M4PSABS8X2B080M4PSABS8X2C080M5PSABS8X2C100M5PSABS8X2D120M5PSAB
Other Trane Furnace codes
All Trane Furnace error codes →
Trane code E3.4: homeowner questions
What does Trane code E3.4 mean?
2nd stage pressure switch (PS2) open when it should be closed. PS2 did not prove on a 2nd stage call (S8X2 allows 45 seconds). The furnace drops to 1st stage, retries after 10 minutes, and after the third failure in the same call stays on 1st stage.
Is it safe to keep using my furnace with code E3.4?
It depends on the cause. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.
Can I reset Trane code E3.4 myself?
You can try one reset (power off for 30 seconds, then on). If Trane code E3.4 comes back, the cause is still there and a licensed technician should check it.
Who can fix Trane code E3.4 near me?
Aurora Star Tech Inc. repairs Trane furnaces in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: Furnace Not Turning On: What to Check · Furnace Blinking Light: What the Flash Codes Mean
Troubleshooting guides
- Blowing cold air All brands · Furnace
- No heat All brands · Furnace
- Short cycling All brands · Furnace
- Reading and clearing fault history - Trane S-Series IFC Trane · Furnace
Source: Trane FNR-SVX003A-EN (S8V2 installer's guide) - section Integrated Furnace Control Display Codes, Table 37 Error codes; Trane FNR-SVX003A-EN (S8V2 installer's guide) - section Troubleshooting (flowcharts); Trane 18-CE14D1-1A-EN (S8B1/S8X1/S8X2 installer's guide) - section Integrated Furnace Control Display Codes, Error Codes. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.