What does code U0291 mean?

Q: What does code U0291 mean?

Lost Communication With Gear Shift Control Module B. U0291 is a generic network communication code indicating that the primary control module (typically the engine or transmission computer) has lost the controller area network (CAN) signal from the gear shift control module B. The computer detects this when it stops receiving the periodic status messages that the shift module is programmed to broadcast, usually for more than a few seconds.

DTC codes / U02xx · Lost communication with a control module / U0291

U0291Lost Communication With Gear Shift Control Module B

U0291 is a generic network communication code indicating that the primary control module (typically the engine or transmission computer) has lost the controller area network (CAN) signal from the gear shift control module B. The computer detects this when it stops receiving the periodic status messages that the shift module is programmed to broadcast, usually for more than a few seconds.

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.