U01AALost Communication With Hybrid/EV Battery Interface Control Module K
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- U01AA covers battery interface control module K, the eleventh board, so only large packs can set it at all. Not every design uses wires for this link: GM's Ultium platform monitors its cells by radio, a system developed with Analog Devices, which according to Wikipedia needs about 90 % less wiring. With such a layout a lost module is a radio node the controller no longer hears; checks then move from harness and plugs to the node's supply, interference and the correct registration of any replacement board. No manufacturer publicly ties U01AA to a vehicle; GM includes it only in the fault bundle of its 2018 hybrid table, which lists module codes up to M, without a monitor entry or MIL type of its own.
- What you may notice
- Battery warning, reduced range and power
- DC fast charging limited or refused
- Likely causes
- LikelyWired link to K interrupted or, in wireless systems, radio link lost
- PossibleReplacement board K not registered with the battery controller
- RareBattery interface control module K 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: €100 – €3,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.