DTC codes / U04xx · Invalid data received from a module / U0402
U0402 means the transmission control module (TCM) is sending data over the vehicle's communication network that other modules consider invalid or implausible. The computer that set the code received a message from the TCM, but the message content failed a rationality or range check, so the receiving module flagged it as untrustworthy.
Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.
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