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DTC codes / U02xx · Lost communication with a control module / U025A

U025ALost Communication With Special Purpose Vehicle Control Module B

U025A is a generic communication fault indicating that the primary control module has lost contact with a special-purpose vehicle control module designated as 'B' on the vehicle's data bus network. The computer sets this code when it expects regular messages from that module but receives none within a defined time window, often because the module is unpowered, disconnected, or the bus wiring is compromised.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaLost communication with a control module

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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