U05ACInvalid Data Received From Vehicle Thermal Management Control Module
- Generic OBD-II code · Network
- Can trigger limp mode
- How the car detects it
- Electrified cars increasingly run cabin, battery and drive-unit cooling from one thermal management controller that commands pumps, valves, fans and the refrigerant circuit; suppliers such as Hirain and Marelli sell such units, Marelli explicitly with OBD compliance. For hybrids, CARB requires the electronic parts used for battery and inverter cooling or heating to be monitored and, where feasible, the cooling performance itself. U05AC is stored when that controller's status or temperature messages reach another module with invalid content. Audi reports the partner U02AB, the thermal management unit 00C5 not reachable, on the 2025/26 A5, Q5 and S5 with a software fix (index entry only). No maker documents U05AC itself. Charging and drive power may be limited to protect the battery.
- What you may notice
- Various warning messages in the cluster
- Reduced charging or drive power
- Climate control not working properly
- Likely causes
- LikelyThermal management controller software out of date
- PossibleFaulty temperature or pressure sensor feeding the controller
- RareController internally faulty
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.