U0142: Lost Communication With Body Control Module B

What it means

A control module has stopped receiving expected messages from body control module B. Body functions managed by that module may be limited or unavailable.

How it works

Body control module B manages body-related functions and shares status messages with other modules over the vehicle network. This code sets when a module does not receive expected messages from BCM B, potentially because its power or ground is interrupted, its network connection is faulty, or system voltage is low.

Common causes

Most likely first.

1. Body control module B power or ground fault
2. Damaged network wiring or connector
3. Body control module B failure
4. Low system voltage

Symptoms

• Body or electrical warning
• Some body functions may be unavailable
• Other communication codes

How to diagnose it

1. Scan all modules and review freeze-frame data to identify when communication with BCM B was lost and whether other modules logged related codes.
2. Check battery condition and charging-system operation, as low voltage can disrupt BCM B communication.
3. Check which modules can communicate with BCM B and test the body functions it manages to see whether the issue is confined to BCM B.
4. Inspect BCM B connectors, power and ground connections, and nearby network wiring for corrosion, looseness, water entry, or physical damage.
5. Using the correct wiring information, test BCM B power and ground under load and check the network circuit for opens, shorts, or poor connections against the manufacturer's specification.
6. If the supply and network tests pass, use the manufacturer's diagnostic procedure to determine whether BCM B itself is faulty.

Common fixes

• Charge or replace a weak battery and correct any charging-system fault.
• Reconnect or clean a loose or corroded BCM B connector and repair damaged wiring.
• Repair a BCM B power or ground fault identified by testing.
• Repair an open, short, or poor connection in the network wiring to BCM B.
• Replace or reprogram BCM B only after testing confirms failure and the vehicle requires programming.

Can I keep driving?

The code alone does not indicate an engine or emissions fault, but functions managed by BCM B may be unavailable. Drive only if essential features such as lighting, visibility, and starting work correctly, and avoid relying on any affected body functions.