U0427 indicates that the Powertrain Control Module (PCM) received invalid data from the vehicle's security control module, which is a communication fault on the CAN network. It does not point to an engine mechanical problem but to a loss of valid security‑module messages.
The security module can develop internal faults that transmit corrupted or no data, triggering the U0427 code.
Corroded terminals, broken wires, or loose connectors between the security module and PCM can cause invalid data reception.
Faulty body control module or other networked components may broadcast erroneous messages that the PCM interprets as invalid.
Insufficient voltage can cause intermittent communication errors on the network, leading to invalid data flags.
A rare internal fault in the PCM’s CAN bus interface can misinterpret valid messages as invalid, but this is uncommon.
Usually not; the code is most often caused by a faulty security module or wiring issue, so PCM replacement is rarely needed.
The vehicle may still start and run, but the immobilizer may prevent starting, and the engine may enter limp mode, so it should be addressed promptly.
A weak key fob battery can cause intermittent communication faults, but it typically does not set U0427; it more often results in keyless entry issues.
Any qualified technician with a scan tool capable of accessing the vehicle’s network can diagnose U0427; dealer tools are not mandatory.