U01A8Lost Communication With Hybrid/EV Battery Interface Control Module I
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- U01A8 is the code for battery interface control module I and is only needed on packs with more than eight monitoring boards. GM's 2018 hybrid table contains it solely inside the fault bundle BICM Loss of Comm (U01A0-U01AC), adding that GM shares software across programs and only codes valid for the vehicle at hand apply; there is no monitor entry of its own, so neither threshold nor MIL type is published for I. Packs of that size exist: according to Wikipedia, the Ultium battery of the Hummer EV holds 24 modules, but which systems really use U01A8 remains undocumented. When it appears, the battery controller has lost the ninth board of its chain while the eight before it still answer. CARB requires separate codes per replaceable unit.
- What you may notice
- Battery or hybrid warning, power limited
- Charging blocked
- Likely causes
- LikelyChain connection between module H and module I interrupted
- PossibleBattery interface control module I defective
- RareBattery controller configured for more boards than fitted
- 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.