What it means
A control module has stopped receiving expected messages from suspension control module B. Suspension functions managed by that module may be limited or unavailable.
At a glance
- Usually lights the warning light of the system that lost communication
How it works
Suspension control module B communicates with other vehicle modules to manage the suspension functions assigned to it. U0139 sets when expected messages from module B are missing, so those suspension functions may be limited or unavailable.
Common causes
Most likely first.
- Suspension control module power or ground fault
- Damaged network wiring or connector
- Suspension control module failure
- Low system voltage
Symptoms
- Suspension warning or message
- Suspension functions may be unavailable
- Other communication codes
How to diagnose it
- Scan all modules and review freeze-frame data for U0139, noting any suspension or low-voltage codes recorded at the same time.
- Check battery condition and charging-system operation because low system voltage can interrupt communication.
- Locate suspension control module B using vehicle service information, then inspect its connector and wiring for corrosion, water, looseness, or damage.
- Check module B's power and ground circuits under load against the manufacturer's specification.
- Test the network wiring to module B for opens, shorts, or poor connections following the manufacturer's procedure.
- If its power, ground, and network circuits are sound, check for module B scan-tool communication before considering replacement or configuration.
Common fixes
- Restore battery or charging-system performance if voltage is low.
- Secure or repair a corroded or damaged connector at suspension control module B.
- Repair damaged network wiring serving module B.
- Repair module B's power or ground supply.
- Replace and configure suspension control module B if it remains unresponsive with sound circuits.
Can I keep driving?
If the suspension warning is on or the vehicle sits unevenly, handles unusually, or rides harshly, limit driving and avoid high speeds or heavy loads. Suspension functions may be unavailable, which can affect stability and ride control.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.