P2AC9
Charge Air Cooler Coolant Temperature Sensor B Circuit Low
Voltage on the charge air cooler coolant temperature B sensor signal line is below the expected window. Wire shorted to ground or sensor short.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: easy
Common causes
Ordered by how often each turns out to be the cause.
- Signal wire shorted to groundCommon
- Internal sensor shortPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Charge Air Cooler Coolant Temp Sensor B
- Wiring Harness
- ECM
P2AC9 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.