U0166low severityNetwork
Lost Communication with Auxiliary HVAC Control Module
on 2012 Toyota Avalon 3.5L V6 · FWD
What this code means
Cannot communicate with auxiliary heater or auxiliary climate module.
Symptoms
- Auxiliary heater not working
- Pre-conditioning not available
- Remote start climate control disabled
Common causes
- Auxiliary HVAC module failure
- CAN bus wiring
- Module power loss
- Fuse blown
Diagnostic steps
- Check auxiliary HVAC fuse
- Test power and ground
- Check CAN wiring
- Test auxiliary heater element
Repair notes
Check fuses for auxiliary climate system.
Other Network codes on this vehicle
U0001
High Speed CAN Communication Bus
U0002
High Speed CAN Communication Bus Performance
U0003
High Speed CAN Communication Bus (+) Open
U0004
High Speed CAN Communication Bus (+) Low
U0005
High Speed CAN Communication Bus (+) High
U0006
High Speed CAN Communication Bus (-) Open
U0007
High Speed CAN Communication Bus (-) Low
U0008
High Speed CAN Communication Bus (-) High
U0009
High Speed CAN Communication Bus Shorted Together
U0010
Medium Speed CAN Communication Bus