U031BSoftware Incompatibility With DC/DC Converter Control Module A
- Generic OBD-II code · Network
- How the car detects it
- DC/DC converter module A moves energy between two voltage levels, in hybrids and mild hybrids typically from the high-voltage or 48 V battery to the 12 V system. U031B means another module does not accept the converter's software. Audi documents it for the 2022-2023 A3, S3 and RS 3 with 48 V mild hybrid: after a 48 V battery replacement, battery management 2 (J1120) may store U031B00, because the updated battery (5WA.915.107.B) runs a validation check of voltage converter A7 that converter software 5WA.959.663 does not answer. With exactly these two part numbers Audi says the code can be ignored (TSB 2068368/1). On other combinations a genuine mismatch can stop the 12 V supply from being charged, so watch for battery or charging warnings. U0298 means lost contact. The MIL normally stays off.
- What you may notice
- Often no symptom, code found during service
- 12 V battery or charging warning possible
- Mild hybrid functions such as start-stop or recuperation limited
- Likely causes
- Likely48 V/HV battery or its management replaced by a newer version the converter software does not support
- PossibleDC/DC converter replaced without programming or coding
- RareConverter software behind the level of the other powertrain modules
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €0 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.