DTC codes / U06xx · Network communication / U063C
U063C is a generic network communication code indicating that a control module on the vehicle's Controller Area Network (CAN) bus has lost contact with the coolant bypass valve actuator labeled B. The module that sets this code expects regular status messages from that actuator, and it has detected that those messages have stopped arriving within the required time window.
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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