U01A2Lost Communication With Hybrid/EV Battery Interface Control Module C
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- U01A2 is stored when battery interface control module C, the third board of the chain, stays silent. How a controller reaches that verdict is spelled out in GM's 2016 hybrid table: the battery system module first logs U179C for one or more missing boards, then orders all boards into a loopback mode that bypasses the daisy chain. A board that answers in this mode still has power and working logic, so the master can separate a broken link from a dead unit and names only the first board it fails to recover; the code passes again once data returns for 100 ms. Audi bulletin 2081028 for the Q5 e (model years 2022 and 2024) lists U01A200 among the codes for modules A to H behind an electrical system malfunction warning.
- What you may notice
- Electrical system or hybrid warning in the instrument cluster
- Reduced drive power or no electric driving
- Code returns immediately after clearing
- Likely causes
- LikelyChain link between module B and module C broken (connector, ribbon, pin)
- PossibleModule C fails the loopback test, board defective
- RareBattery controller software that misreads the chain (update available)
- 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: €100 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.