Network
generic / SAE
U0664
Lost Communication With Rear HVAC Air Cutoff Actuator
The vehicle bus reports loss of communication with smart rear HVAC air cutoff actuator (shuts the rear duct entirely off). Cutoff cannot be commanded; rear airflow stays in last-known position.
SystemNetwork
Typegeneric / SAE
GroupU0
Range / number6 / 64
Possible causes
- Bus wiring open or shorted high
- Module without power or ground medium
- Module failed medium
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
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 80–600 €
- Estimated time: 0.5–2 h
- Component: rear hvac cutoff actuator
- Component: vehicle bus wiring
- drive cycle required
Sources
References
sae:J2012