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U0243 — Lost Communication Parking Assist Control Module B

Generic OBD-II · all makesNetwork / communication

Code U0243 indicates that the vehicle's primary communication network has lost contact with the Parking Assist Control Module B. This means the computer responsible for managing specific parking sensors or cameras is not sending or receiving data on the CAN bus.

Symptoms

What causes it — most likely first

1. Wiring Harness Damage

Physical damage, corrosion, or rodent chewing of the wiring connecting the module to the network, often occurring in the bumper or lower chassis areas.

2. Blown Fuse or Power Loss

A blown fuse or faulty relay preventing the Parking Assist Control Module B from powering up and communicating.

3. Faulty Control Module B

Internal electronic failure of the Parking Assist Control Module B itself.

4. CAN Bus Interference

Shorts or open circuits in the vehicle's communication network causing data packets to be lost.

5. PCM/ECM Failure

A failure in the main engine control module's communication gateway, though this is extremely rare for this specific code.

How it's diagnosed

  1. Inspect the vehicle's bumpers and lower chassis for visible wiring damage or impact marks.
  2. Check the fuse box for any blown fuses associated with the parking assist or convenience systems.
  3. Verify the power and ground connections at the Parking Assist Control Module B using a multimeter.
  4. Perform a continuity test on the CAN high and CAN low wires between the module and the gateway.
  5. Use a diagnostic scan tool to check for accompanying U-codes that might indicate a broader network failure.

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make

Frequently asked

Can I still drive the car with this code?

Yes, the vehicle remains drivable, but the parking assistance and safety alerts will be non-functional.

Does this mean I need to replace my engine computer (PCM)?

No. While the PCM manages the network, U0243 is almost always caused by a local wiring issue or a failure within the specific parking module, not the PCM.

Why is it called 'Module B'?

Many vehicles use multiple modules to manage different zones of the car (e.g., front vs. rear sensors) or different functions of the parking system.