U05AAInvalid Data Received From Charge Air Cooler Coolant Pump
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- Engines with a water-cooled charge air cooler use an electric pump, often a LIN slave of the engine controller, to move coolant through the low-temperature circuit. CARB requires the charge air cooling to be checked for performance and its electronic parts to be monitored. U05AA is set when the pump reports speed, current or fault bits that do not make sense. Public maker documentation exists for the partner U02A9: GM's 2025 tables declare lost LIN contact after 2.5 s without a pump response, Type A; Ram 1500 owners see a check engine light with U02A9 and P023B from pushed-out terminals at the pump connector; Mercedes links U02A900 on GLC and GLE to the PTCU software or LIN wiring. None documents U05AA itself. Expect reduced boost if intake air runs hot.
- What you may notice
- Check engine light on
- Reduced engine power in hot conditions
- Coolant warning or radiator fan running at full speed
- Likely causes
- LikelyPushed-out or corroded terminals at the pump connector
- PossibleFault elsewhere on the shared LIN bus or in the master module software
- PossiblePump electronics or motor faulty
- 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: €60 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.