Network, generic

U0122 Lost Communication With Vehicle Dynamics Control Module

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U0122 tells you that a networked controller, often the engine or hybrid ECU, has stopped receiving the cyclic frames of the stability control unit (ESC/VSC/ASC, usually combined with the ABS hydraulic unit). Mitsubishi's 2023 Outlander PHEV documents it in the PHEV-ECU: with 10–16 V present for at least 5 s and the motor switch on, a broken link to the ABS/ASC unit lasting 2 s or more stores U0122-00, and Mitsubishi verifies the repair with an OBD-II test drive pattern. Saab's 9-5 code list names the partner Vehicle Stability Control Module, and Subaru released ECM software for the 2019 Ascent that changes how its ECM detects U0122. U0121 and U0129 point at the ABS and brake modules instead. Stability and traction aids usually switch off.

Likely causes

Missing fuse, supply or ground at the stability/ABS unit
Damaged CAN wiring or faulty gateway between the bus segments
Receiving controller software reports the loss too eagerly (update exists, e.g. Subaru)
Stability control module internally faulty

Symptoms

  • ESC, traction control and ABS warning lamps on
  • Stability and traction control unavailable
  • MIL on in some vehicles (engine or hybrid ECU stores the code)

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–1,800
Time0.5–4 h

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

Parts involved

vehicle dynamics modulecan bus wiring

Related codes

U0316U0416U0121U0129U0126

References: mitsubishitechinfo.com, static.nhtsa.gov, saabwisonline.com, performanceparts.ford.com.