What does code U01A1 mean?

DTC codes / U01xx · Lost communication with a control module / U01A1

U01A1Lost Communication With Hybrid/EV Battery Interface Control Module B

U01A1 is a generic network communication code indicating that one control module on the vehicle's high-speed data bus has stopped receiving messages from the Hybrid/EV Battery Interface Control Module B. The module that set the code detected a loss of the periodic serial data messages it expects from that battery interface module, not necessarily a failure of the battery pack itself.

SystemNetwork

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyProfessional

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.