OBD-II code · Network
U0663 Lost Communication With Rear Mode Actuator
The vehicle bus reports loss of communication with smart rear HVAC mode (vent/floor/defrost) actuator. Rear air distribution falls back to a default mode.
Is it safe to drive with U0663?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyBus wiring open or shorted
- PossibleModule without power or ground
- PossibleModule failed
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–2 h
- Emissions test
- Usually unaffected
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Rear Mode Actuator, Vehicle Bus Wiring
Related codes
- U0660Lost Communication With Left Rear Temperature Actuator B
- U0661Lost Communication With Right Rear Temperature Actuator A
- U0662Lost Communication With Right Rear Temperature Actuator B
- U0664Lost Communication With Rear HVAC Air Cutoff Actuator
- U0665Lost Communication With Fuel Rail Pressure Sensor Bank 2
- U0666Lost Communication With Reductant Pressure Sensor
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.