U01A9Lost Communication With Hybrid/EV Battery Interface Control Module J
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- U01A9 stands for battery interface control module J, the tenth board. Apart from wiring, a typical trigger after repairs is configuration: monitoring chips in a chain usually get their address when communication starts. NXP's MC33771C cell controller, for instance, receives its address during initialisation and supports up to 63 nodes per chain, and a Nuvoton patent (US20210184474) describes addresses handed out one after another at start-up in daisy-chained supervisors. A replaced or reordered board that fails to take its slot may therefore go missing for the master. Software mismatch with the same board has its own code, U0342. No manufacturer documents U01A9 with a monitor of its own; GM only lists it in the 2018 bundle BICM Loss of Comm.
- What you may notice
- Code appears right after battery repair or module replacement
- Vehicle not ready to drive or power limited
- Likely causes
- LikelyChain connection between module I and module J interrupted
- PossibleBoard J not addressed or registered after module replacement
- RareBattery interface control module J defective
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €0 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.