U0165Lost Communication With HVAC Control Module - Rear
- Generic OBD-II code · Network
- How the car detects it
- U0165 names a second climate unit, the rear HVAC control module, fitted in vans, minivans and large SUVs that heat and cool the back rows with their own blower and flaps. The code says this rear module has gone quiet on the network; the front unit is covered by U0164. No manufacturer documents U0165 publicly, and the GM/Saab and Ford code lists checked here skip it. The trigger follows the pattern GM gives for every code from U0100 to U02FF: the module's periodic availability message fails to arrive while the supply lies between 9 and 16 V, and each listener records the fault. Rear vents then stop reacting or keep a fixed setting, while the front climate and the engine run normally. No MIL is expected.
- What you may notice
- Rear climate controls without function
- Rear blower stuck off or at one speed
- Front climate keeps working normally
- Likely causes
- LikelyRear HVAC module without power or ground (fuse, connector)
- PossibleBus wiring to the rear unit chafed under trim or at sliding-door area
- RareVehicle coded for rear climate that is not fitted
- RareRear HVAC control module faulty
- Repair
- Medium · Usually a job for a workshop.Typical cost: €40 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.