What it means
A control module has detected that the software in Body Control Module B is incompatible with its own software or configuration. The affected body functions depend on the vehicle.
How it works
Body Control Module B handles a designated set of body or convenience functions, which varies by vehicle. U0339 is stored when another module detects that BCM B's software or configuration is incompatible with the version it expects, potentially affecting the functions assigned to that body controller.
Common causes
Most likely first.
- Incorrect or incompatible Body Control Module B software
- Module replacement without required programming or configuration
- Incorrect module part number
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
How to diagnose it
- Record freeze-frame data and scan all modules for body-system, communication, and configuration codes to identify which functions or controllers are involved.
- Check whether the fault followed body-control-module or electrical work, and verify that Body Control Module B has the correct part number for the vehicle.
- Use a capable scan tool to read BCM B's software and configuration identifiers and compare them with manufacturer information.
- Inspect accessible low-voltage connectors and wiring for BCM B for looseness, corrosion, or damage, and check which body functions are inoperative.
- If the hardware and connections are correct, have BCM B programmed or configured for the vehicle, then verify the affected body functions and rescan.
Common fixes
- Reconnect or repair a loose or damaged accessible BCM B connector or harness.
- Replace BCM B if its part number is incorrect for the vehicle.
- Program or configure BCM B for the vehicle's installed equipment.
- Apply a manufacturer-approved software update to resolve the mismatch.
Can I keep driving?
Driving may be possible if essential controls work normally, but do not drive if the fault affects lighting, wipers, door latches, or another function needed for safe operation. Unavailable body functions may persist or worsen until the module configuration is corrected.
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.