HomeTrouble CodesU0143

U0143 — Lost Communication Body Control Module C

Generic OBD-II · all makesNetwork / communication

U0143 means a control module on the vehicle network has stopped receiving messages from Body Control Module C. It is a communication (U-code) fault, not a sensor or emissions failure, and usually points to a power, wiring, or module problem rather than the engine computer.

Symptoms

What causes it — most likely first

1. BCM C internal fault or loss of power/ground

The Body Control Module C may have failed internally, lost its main power feed, or developed a poor ground, preventing it from communicating on the data bus.

2. Open or short in the BCM C communication circuit

Damage, corrosion, pin-fit issues, or a break in the CAN/data-bus wiring between BCM C and the rest of the network can interrupt messages.

3. Low system voltage or charging/battery problem

Weak batteries, poor alternator output, or loose battery connections can cause voltage drops that make modules drop off the network and set communication codes.

4. Connector or harness issue at BCM C

Water intrusion, backed-out terminals, spread pins, or corrosion at the BCM C connectors can disrupt both power and data signals.

5. Fault in another network module causing bus disruption

A shorted or failing module elsewhere on the same data bus can sometimes pull the network down and cause loss-of-communication codes for BCM C, though this is less common.

How it's diagnosed

  1. Confirm the code and record all stored U-codes; note which module set U0143 and whether symptoms are constant or intermittent
  2. Check battery voltage, state of charge, and charging system; clean and tighten battery terminals and major grounds
  3. Inspect BCM C connectors, pins, and grounds for corrosion, damage, or poor fit; verify power feeds with a wiring diagram
  4. Test the communication bus for proper voltage, resistance, and continuity between BCM C and the network; check termination resistors if applicable
  5. Wiggle-test the harness between BCM C and related modules while monitoring communication to find intermittent opens or shorts
  6. If all wiring and power are good, evaluate BCM C itself; only consider replacing the module that set the code if every other possibility has been ruled out

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make

Frequently asked

Can a weak battery cause U0143?

Yes. Low system voltage is a common cause of communication codes. Test and fully charge or replace the battery if it fails load testing, and verify charging system output before replacing modules.

Will U0143 prevent my car from starting?

It can, depending on the vehicle. If BCM C is involved in security, immobilizer, or start-enable functions, the engine may crank but not start, or start functions may be limited.

Do I need a new PCM/ECM for U0143?

Usually no. U0143 concerns Body Control Module C communication, so the problem is most often the BCM C itself, its wiring, or network voltage. Replacing the PCM/ECM rarely fixes this code and should only be considered after everything else is ruled out.

Is it safe to drive with U0143?

Often yes for short trips, but body and convenience functions may not work correctly. If the vehicle will not start reliably or safety systems are affected, it should be diagnosed before driving.