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U0139 Lost Communication With Suspension Control Module B

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

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.

Likely causes

Suspension module software locks up, recovers after a fuse reset (GM PIT6007)
High resistance or open in the module wake-up line (GM circuit 5986)
Fuse, supply, ground or CAN wiring of the damping module faulty
Suspension control module B internally faulty

Symptoms

  • Check-engine lamp, often without any other symptom (GM)
  • Service Suspension message, adaptive damping inactive
  • Harsher or softer ride than usual

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€30–2,000
Time0.3–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

suspension module bcan bus wiring

Related codes

U043AU0132U0133

References: gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.