U0431 means that a control module (usually the PCM or another ECU) has received data from the Body Control Module that fails validation checks such as incorrect message length, checksum, or out‑of‑range values. It is a communication fault on the vehicle’s CAN network, not a sensor or actuator failure.
Internal circuit failure, memory corruption, or a defective CAN transceiver inside the BCM can cause it to transmit invalid frames.
Open circuits, short to power/ground, corrosion, or loose pins in the harness can distort or interrupt the BCM's messages.
Low battery voltage, blown fuse, or a corroded ground point can cause the BCM to operate out of spec and send garbled data.
A missing or incorrect termination resistor, bus short, or another node injecting errors can corrupt the BCM's transmission.
Less commonly, the PCM's CAN transceiver or related circuitry may be defective, causing it to misinterpret valid BCM data as invalid.
No. The PCM is rarely at fault for this code; most cases stem from the BCM, its wiring, power/ground, or CAN bus issues. Replacing the PCM should be considered only after those areas have been verified as good.
Yes. If the fuse supplying power to the BCM opens, the module may operate at low voltage or reset intermittently, leading to invalid transmissions that trigger U0431.
Only if the BCM’s internal memory was corrupted or if a software update is required by the manufacturer. Correcting wiring or power issues often restores normal communication without reprogramming.
Clearing the DTC turns off the warning light, but if the underlying communication fault persists, the code will return once the invalid data is detected again.