E11
Trane
Output Relay Failure
Thermostat displays E11 and certain stages of heating or cooling will not engage
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Failed internal relay on thermostat for Y1/Y2/W1/W2/G, Overcurrent from shorted field wiring, Burned relay contacts from repeated high load, Miswired thermostat outputs
How to Fix / Troubleshooting
Safety: Turn off power to the HVAC system before working on wiring.
- Step 1 – Identify affected output: Note which function is not working (e.g., first-stage cool, fan, heat). Check the thermostat diagnostics to see which output is faulted.
- Step 2 – Inspect field wiring: At the thermostat and indoor unit, inspect the corresponding control wire (Y, W, G, etc.) for shorts to ground or other conductors.
- Step 3 – Test output manually: In installer test mode, command the affected output ON and measure voltage between R and the output terminal at the thermostat. If no voltage change occurs and wiring is good, the internal relay is likely failed.
- Step 4 – Correct any shorts: Repair or replace damaged thermostat cable and ensure no bare copper is exposed at terminals.
- Step 5 – Replace thermostat if relay is bad: The output relays are not field-repairable; replace the thermostat with a compatible Trane smart model.
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Repair Difficulty
Medium
3/5
Required Part
Trane Smart Thermostat
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