U02A9Lost Communication With Charge Air Cooler Coolant Pump A
- 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
- Water-cooled charge air coolers need an electric pump in the low-temperature circuit, normally run by the engine controller as a LIN node. U02A9 means the pump has stopped answering. GM's 2025 tables (25OBDG04B) declare it after 2.5 s without a response while the pump is enabled and the supply is 11 to 18 V, and rate it Type A. GM bulletin 23-NA-102 for 2022 to 2025 Silverado, Sierra, Tahoe, Suburban, Yukon and Escalade with the 3.0 L diesel traces it to water entering the M10 pump connector, with or without LIN code U1345. FCA's Ram 1500 case shows pushed-out terminals at connector D2476A; on 2019 Jeep Renegades without grille shutters, an exposed inline connector corrodes. Mercedes reflashes the PTCU on the GLC. CARB requires charge air cooling to be monitored. Expect a MIL and less boost.
- What you may notice
- MIL on
- Reduced boost or hesitation at high load
- Coolant warning or fan running at full speed on some models
- Likely causes
- LikelyWater or corrosion in the pump connector or an open inline connector
- PossibleTerminals pushed out of the pump connector
- PossibleSoftware of the LIN master controller needs an update
- RareCharge air cooler pump electronics failed
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €20 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.