P0A7BBattery Energy Control Module Requested MIL Illumination
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P0A7B is a request code: the battery energy control module, which has found an emissions-relevant fault of its own, asks the engine control module to switch on the MIL, and the engine controller stores P0A7B. The actual cause sits in a separate code in the battery module. GM documents this on the 2024-25 Corvette E-Ray: P0A7B in the K20 engine controller appears together with P0E3C in the battery module, caused by air trapped around the battery coolant pump after a repair; purging the air is the fix. Subaru reports P0A7B in the engine controller of the 2014 XV Crosstrek Hybrid alongside battery and drive motor codes after a frozen power relay. Diagnose the battery module codes first. P0AC4 is the matching request from the hybrid control module.
- What you may notice
- MIL on
- Additional codes stored in the battery control module
- Likely causes
- LikelyEmissions-relevant fault stored in the battery energy control module
- PossibleAir trapped at the battery coolant pump (Corvette E-Ray, with P0E3C)
- RareFrozen power supply relay of the drive motor control module (Subaru Crosstrek Hybrid)
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.