U0138 code meaning
Lost Communication With All Terrain Control Module
What U0138 means
U0138 is logged when another module no longer receives the all-terrain control module, the unit behind the selector that lets the driver pick a terrain or drive mode such as snow, sand or mud and then adapts traction control, throttle response and shift points. Ford lists U0138 in the OBD code tables of its 2014 vehicles and marks it as available in all three self-test modes, without an entry in the lamp column. More public manufacturer detail is missing. CARB treats such a link as a digital input whose loss of communication must carry its own code. Implausible data from this module is U0439; the transfer case and AWD clutch use U0102 and U0114. The mode selector stops working and a 4WD or traction warning appears.
U0138 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0138
- Terrain or drive mode cannot be selected
- 4WD or traction control warning lamp
Common causes of U0138
- Most likelyFuse, supply, ground or CAN wiring of the terrain module faulty
- PossibleLoose or corroded connector at the module or the mode selector
- Less likelyAll-terrain control module internally faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
All terrain moduleCAN bus wiring
What each part of U0138 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 38 | The exact fault in that area. |
What to do next
- Note U0138 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U0138
What does U0138 mean?
U0138 means "Lost Communication With All Terrain Control Module". U0138 is logged when another module no longer receives the all-terrain control module, the unit behind the selector that lets the driver pick a terrain or drive mode such as snow, sand or mud and then adapts traction control, throttle response and shift points. It is a generic code, so it means the same on every make.
Is it safe to drive with U0138?
U0138 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0138 fail an emissions test?
U0138 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U0138 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U0138 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.