U0136 code meaning
Lost Communication With Differential Control Module - Rear
Network system Generic code U01xx codes Check engine light
What U0136 means
U0136 is set when a listener misses the rear differential control module, which operates an electronic limited-slip or twin-clutch rear drive unit. GM's 2019 tables document it in the ECM of the Cadillac XT4 (LSY engine): if message $1CF from the rear drive module stays absent for 10 s while bus A is active and supply exceeds 11 V, the ECM stores U0136 as a Type B fault, so the MIL comes on after two trips. Saab's 2011 9-5 list (XWD all-wheel drive) also names the rear differential module and adds byte 71 for invalid data. Implausible rear-differential data has its own code U0437; the front axle uses U0135. Rear torque distribution switches off with a warning, and the car usually continues with front-wheel drive.
U0136 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0136
- AWD or rear differential warning
- Car drives with front-wheel drive only, less traction
- MIL after two trips on GM vehicles
Common causes of U0136
- Most likelyFuse, supply, ground or CAN wiring of the rear drive module faulty
- PossibleCorroded or damaged connector at the rear axle, exposed to spray water
- Less likelyRear differential 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
Rear differential moduleCAN bus wiring
What each part of U0136 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 36 | The exact fault in that area. |
What to do next
- Note U0136 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 U0136
What does U0136 mean?
U0136 means "Lost Communication With Differential Control Module - Rear". U0136 is set when a listener misses the rear differential control module, which operates an electronic limited-slip or twin-clutch rear drive unit. It is a generic code, so it means the same on every make.
Is it safe to drive with U0136?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will U0136 fail an emissions test?
U0136 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 U0136 to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will U0136 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.