What the code means
Err 67.03: External temperature sensor fault
The Trane variable-speed alert table identifies EXT T SENSE as an external temperature sensor out-of-range condition.
Troubleshooting code
Back to all 4TWV8X24A1 error codes
Trane 4TWV8X24A1 Err 67.03 troubleshooting
External temperature sensor fault. Use this page to document the issue and prepare for service. GreenFlow should handle diagnosis for electrical, refrigerant, lockout, or recurring conditions.
Safe checks before calling
- Confirm the thermostat is on, set correctly, and calling for heating or cooling.
- Check the air filter and visible return-air path for obvious airflow restrictions.
- Look around the outdoor unit for leaves, snow, ice, or other visible obstructions without opening the cabinet.
- Take photos of the thermostat, outdoor unit, nameplate, and any visible flash pattern before scheduling service.
When to stop and call GreenFlow
Call GreenFlow if the code repeats, the system is locked out, heating or cooling is not restored, there is ice buildup, electrical odor, unusual noise, or any issue involving pressure switches, sensors, wiring, refrigerant, reversing-valve operation, or warranty coverage.
Share the visible code, model and serial number if available, photos, current symptoms, and whether the issue affects heating, cooling, or both.
Err 67.03 questions
What does Err 67.03 mean on a Trane 4TWV8X24A1?
The Trane variable-speed alert table identifies EXT T SENSE as an external temperature sensor out-of-range condition.
What should I safely check before scheduling service?
Check thermostat status, filter condition, visible outdoor-unit obstructions, and take photos of the flash pattern and nameplate. Do not open electrical panels or refrigerant-side components.
When should GreenFlow handle this code?
Call GreenFlow if the code repeats, the system is locked out, heating or cooling is not restored, there is ice buildup, electrical odor, unusual noise, or any issue involving pressure switches, sensors, wiring, refrigerant, reversing-valve operation, or warranty coverage.
Need help with this code?
GreenFlow can review the code, photos, equipment access, and symptoms before scheduling the right next step.
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