OBD-II code · Network
U0138 Lost Communication with All Terrain Control Module
The terrain mode / 4WD mode controller has dropped off the bus. Off-road and traction modes can no longer be selected; vehicle defaults to standard 2WD/AWD behaviour.
Is it safe to drive with U0138?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyModule unpowered
- Less likelyGateway module routing CAN messages incorrectly
- Less likelyCAN terminating resistor (120 Ω) drifted out of spec
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
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–3 h
- Emissions test
- Usually unaffected
- Parts involved
- Terrain Control Module, Can Bus Wiring
Related codes
- U0135Lost Communication with Parking Brake Control Module
- U0136Lost Communication with Park Brake Module B
- U0137Lost Communication with Trailer Brake Control Module
- U0139Lost Communication with Active Roll Control Module
- U013CLost Communication With Accelerator Pedal Module
- U013DLost Communication With Vacuum Sensor A
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.