U0139 code meaning
Lost Communication With Suspension Control Module B
Network system Generic code U01xx codes Check engine light
What U0139 means
U0139 reports lost contact with suspension control module B, at GM the semi-active damping system (SADS). GM's 2025 tables let the ECM watch two SADS messages, $035 with a 10 s limit and $364 with 325 ms, and set U0139 as Type B with the MIL after two trips; the EBCM treats missing damper frames for 250 ms as Type C. Bulletins PIT6007 and PIT6007A (2020–2024 Corvette, Escalade, Tahoe, Suburban, Yukon with Magnetic Ride Control) describe a check-engine lamp with U0139 in the ECM and no other symptom, cleared by pulling the K19 module fuse for one minute. PIT5457 lists it with high resistance in wake-up circuit 5986. Saab and Ford's 2014 list carry the code too. Damping then usually stays at a fixed setting.
U0139 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.3 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0139
- Check-engine lamp, often without any other symptom (GM)
- Service Suspension message, adaptive damping inactive
- Harsher or softer ride than usual
Common causes of U0139
- Most likelySuspension module software locks up, recovers after a fuse reset (GM PIT6007)
- PossibleHigh resistance or open in the module wake-up line (GM circuit 5986)
- PossibleFuse, supply, ground or CAN wiring of the damping module faulty
- Less likelySuspension control module B internally faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Suspension module bCAN bus wiring
What each part of U0139 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 39 | The exact fault in that area. |
What to do next
- Note U0139 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 U0139
What does U0139 mean?
U0139 means "Lost Communication With Suspension Control Module B". U0139 reports lost contact with suspension control module B, at GM the semi-active damping system (SADS). It is a generic code, so it means the same on every make.
Is it safe to drive with U0139?
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 U0139 fail an emissions test?
U0139 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 U0139 to fix?
Difficulty: medium. A typical repair takes 0.3 to 4 hours of work. This is a job for a workshop.
Will U0139 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.