A weak or failing battery or poor battery terminal connection causing low voltage to the Active Roll Control Module.; Corroded, loose, or damaged electrical connectors at the Active Roll Control Module or its inline harness connectors.; A broken, chafed, or shorted wire in the CAN bus circuit between the primary control module and the Active Roll Control Module.; A failed Active Roll Control Module due to internal electronic fault or water intrusion.; A blown fuse or faulty relay that supplies power to the Active Roll Control Module.; A fault in another module on the same CAN bus segment that is disrupting communication for all modules.; Aftermarket accessories or poor previous repairs that have disturbed the CAN bus wiring.

DTC codes / U01xx · Lost communication with a control module / U0139

U0139Lost Communication with Active Roll Control Module

Q: What does code U0139 mean?

Lost Communication with Active Roll Control Module. U0139 is a communication fault where the primary control module has lost contact with the Active Roll Control Module over the vehicle's Controller Area Network (CAN) data bus. The computer has detected that the module is not responding to periodic status messages, which prevents the system from commanding the hydraulic or electric actuators that reduce body roll during cornering.

U0139 is a communication fault where the primary control module has lost contact with the Active Roll Control Module over the vehicle's Controller Area Network (CAN) data bus. The computer has detected that the module is not responding to periodic status messages, which prevents the system from commanding the hydraulic or electric actuators that reduce body roll during cornering.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaLost communication with a control module

Symptoms you may notice

The stability control or traction control warning light illuminates steadily on the dashboard.
A message such as 'Active Roll Control Unavailable' or 'Service Suspension System' appears in the driver information center.
The vehicle may feel more prone to body lean or understeer during cornering because the roll control system is disabled.
The ride may become firmer or harsher over uneven surfaces if the system defaults to a fixed damping mode.
Often no symptoms besides the warning light, especially if the failure is intermittent or only affects communication at key-on.
Other unrelated warning lights may appear if the lost module shares a bus segment with other controllers.

Common causes, most likely first

A weak or failing battery or poor battery terminal connection causing low voltage to the Active Roll Control Module.
Corroded, loose, or damaged electrical connectors at the Active Roll Control Module or its inline harness connectors.
A broken, chafed, or shorted wire in the CAN bus circuit between the primary control module and the Active Roll Control Module.
A failed Active Roll Control Module due to internal electronic fault or water intrusion.
A blown fuse or faulty relay that supplies power to the Active Roll Control Module.
A fault in another module on the same CAN bus segment that is disrupting communication for all modules.
Aftermarket accessories or poor previous repairs that have disturbed the CAN bus wiring.

How to diagnose and fix it

Perform a battery and charging system test to confirm stable voltage, and clean and tighten battery terminals as needed.
Use a scan tool to read all modules and record any other communication codes, then clear codes and verify whether U0139 returns immediately.
Visually inspect the Active Roll Control Module connectors and harness for corrosion, loose pins, or damage, and check the module's power and ground circuits with a multimeter.
Check the fuse and relay that supply power to the Active Roll Control Module, replacing any blown fuse or faulty relay after confirming no short to ground.
Measure CAN bus resistance and voltage at the Active Roll Control Module connector to verify bus integrity, and repair any open or shorted wiring.
If wiring and power are confirmed good, substitute a known-good Active Roll Control Module or perform a module swap test to see if communication is restored.
After repair, clear codes and perform a road test to confirm the Active Roll Control Module communicates and the system operates correctly.

Why the roll control module goes silent

A low or failing battery is a common cause of U0139 because the Active Roll Control Module may drop offline during engine cranking, setting a communication code without any hard fault in the module itself.
The code does not always mean the Active Roll Control Module is defective; a single chafed CAN wire or a corroded connector pin can interrupt communication while the module remains fully functional.
Technicians sometimes replace the Active Roll Control Module only to find the real fault is a failed power relay or a blown fuse that also feeds other modules on the same circuit.
If other modules on the same CAN bus are also setting communication codes, the fault is likely a shared bus wiring issue rather than the Active Roll Control Module alone.
Aftermarket alarms, remote starters, or phone chargers plugged into the diagnostic port can disturb CAN bus voltage and cause intermittent U0139 without any physical damage.

Can I keep driving with U0139?

You can usually drive the vehicle with U0139 because the Active Roll Control system defaults to a passive mode, but handling will be less controlled in corners and emergency maneuvers. Avoid aggressive driving, towing, or heavy loads until the fault is repaired, and have the system diagnosed promptly if the warning light is accompanied by other stability control warnings.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.