What it means
A receiving module detected implausible data from body control module C. BCM-relayed signals (door/lock/lighting state, ignition, theft) fail plausibility checks and are rejected.
How it works
Body Control Module C shares body-system status data with other modules over the vehicle network. U0444 means a receiving module has rejected a message from BCM C as implausible; the affected status could involve doors, lighting, ignition, or security, depending on the vehicle's design.
Common causes
Most likely first.
- Module internal fault or sensor input drift
- Software version mismatch after replacement
- Gateway module routing CAN messages incorrectly
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
- Scan all modules and save freeze-frame and communication codes to identify the receiver and the body function associated with the rejected BCM C data.
- Compare BCM C live data for relevant door, lighting, ignition, or security states with the actual vehicle condition.
- Inspect BCM C connectors, grounds, power supply connections, and network wiring for looseness, corrosion, or damage.
- Check for gateway and network communication faults involving BCM C.
- If BCM C or a related module was recently replaced, confirm software compatibility and configuration, then test affected functions using the manufacturer's procedure.
Common fixes
- Repair damaged or corroded BCM C wiring, grounds, or connectors.
- Correct a gateway or network fault confirmed to interfere with BCM C messages.
- Update or configure replacement BCM C software as required for the vehicle.
- Repair a confirmed BCM C input or internal fault.
- Replace BCM C only after diagnosis rules out wiring, network, and configuration causes.
Can I keep driving?
Check the vehicle's lighting, door, ignition, and security functions before driving, since BCM C data may affect one or more of them. Do not drive if lighting or another affected function makes the vehicle unsafe.
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.