What does code U04A9 mean?

DTC codes / U04xx · Invalid data received from a module / U04A9

U04A9Invalid Data Received From Hybrid/EV Battery Interface Control Module I

U04A9 is a communication fault where the vehicle's main control modules receive invalid or corrupted data from the Hybrid/EV Battery Interface Control Module I, which is the electronic unit that monitors and reports on the high-voltage battery pack. The code does not mean the battery itself has failed; it means the data stream from that interface module is missing, garbled, or fails plausibility checks, so other modules cannot trust the battery information they need to manage the hybrid system.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaInvalid data received from a 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.