Trane Error Code E4.0: Main high limit open (Furnace)
Trane error code E4.0 on a furnace means: Main high limit open. It is also called Trane diagnostic code E4.0.
Homeowner? What Trane code E4.0 means for you
Call a technician Your furnace is reporting: Main high limit open. The furnace has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.
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 E4.0 mean?
The main thermal limit opened because it sensed too much heat. Check both 1st and 2nd stage operation.
Applies to: Trane S8V2 only
Common causes of Trane code E4.0
- Dirty filter or blower wheel
- External static above nameplate, undersized ducts
- Return air above 85 F
A technician checks these and 3 other possible causes on site before replacing any part.
Trane models that use code E4.0
S8V2A040M3PCBS8V2A040M3PDS8V2B060M4PCBS8V2B060M4PDS8V2B080M4PCBS8V2B080M4PDS8V2C080M5PCBS8V2C080M5PDS8V2C100M5PCBS8V2C100M5PDS8V2D120M5PCBS8V2D120M5PD
Other Trane Furnace codes
All Trane Furnace error codes →
Trane code E4.0: homeowner questions
What does Trane code E4.0 mean?
Main high limit open. The main thermal limit opened because it sensed too much heat. Check both 1st and 2nd stage operation.
Is it safe to keep using my furnace with code E4.0?
It depends on the cause. The furnace has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.
Can I reset Trane code E4.0 myself?
You can try one reset (power off for 30 seconds, then on). If Trane code E4.0 comes back, the cause is still there and a licensed technician should check it.
Who can fix Trane code E4.0 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). 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.