Ecobee
-
✅ Safe to Use
Ecobee - Error Code AUX
Ecobee Thermostat error code AUX: Auxiliary heat active.
Is it safe?
✅ Safe temporarily
Safe to use on cold settings temporarily. Heating element failure is a common DIY repair.
Can I fix it?
DIY Possible
Tools: Multimeter, Screwdriver set, Nut driver
Repair cost
DIY: $20–$100 (element or thermistor)
Pro: $100–$300
⏱ 30–60 min
What Does Error Code AUX Mean?
Ecobee Thermostat error code AUX: Auxiliary heat active.
Part that typically fails: Heating element / thermal fuse / thermistor
Safe to use on cold settings temporarily. Heating element failure is a common DIY repair.
Symptoms You May Notice
- ⚠️ Thermostat showing error
- ⚠️ HVAC system not responding
- ⚠️ Temperature control not working
Troubleshooting Steps
- 1 Check your owner's manual for model-specific guidance on error code reset procedures
- 2 If the error persists after reset and basic checks, contact a qualified technician
🛠️ Tools needed: Multimeter, Screwdriver set, Nut driver
· Time: 30–60 min
⚡ Quick tip: Always try a full power reset first — turn the unit off at the breaker, wait 30 seconds, restore power.
Frequently Asked Questions
What does Ecobee Thermostat error code AUX mean? ▼
Error code AUX on a Ecobee thermostat indicates: Auxiliary heat active. The unit has detected this condition and has limited or stopped operation to prevent further damage.
How do I fix Ecobee Thermostat error code AUX? ▼
Start by powering the unit off for 30 seconds and restarting. If error AUX returns, the underlying cause (auxiliary heat active) needs to be addressed. Check wiring connections and filters first before replacing components.
Is Ecobee error code AUX serious? ▼
It depends on the root cause. Some AUX errors resolve with a reset. Others indicate a failed component that requires professional repair. Don't continue operating with this error — it can lead to further damage.