What does code U0633 mean?

Q: What does code U0633 mean?

Lost Communication With Fan 2. U0633 is a network communication code indicating that a control module on the vehicle's Controller Area Network (CAN) bus has lost contact with the Fan 2 control module, which is typically responsible for the second cooling fan or a secondary fan circuit. The module that sets this code has detected that expected periodic messages from the Fan 2 module have stopped arriving within the required time window, so it flags a communication failure rather than a direct fan malfunction.

DTC codes / U06xx · Network communication / U0633

U0633Lost Communication With Fan 2

U0633 is a network communication code indicating that a control module on the vehicle's Controller Area Network (CAN) bus has lost contact with the Fan 2 control module, which is typically responsible for the second cooling fan or a secondary fan circuit. The module that sets this code has detected that expected periodic messages from the Fan 2 module have stopped arriving within the required time window, so it flags a communication failure rather than a direct fan malfunction.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaNetwork communication

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.