P2ACBCharge Air Cooler Coolant Temperature Sensor B Intermittent/Erratic
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2ACB covers a sensor B signal that jumps or briefly drops out instead of following the slow temperature changes of a coolant loop. The title, without the word circuit, also includes erratic values while the wiring stays intact. No maker publishes the B-side check. GM's 2025 diesel table shows how the A-side version (P00E2) works: it builds moving limits around the last good reading using the sensor's filter time and counts 60 failed samples out of 75 against them, Type B. A test of this kind only runs while no steady circuit fault is present, so P2AC9 or P2ACA take priority. Typical causes are a terminal with poor contact tension, a connector loosened by vibration or coolant that has crept into the plug. Wiggle the harness while watching live data.
- What you may notice
- Check engine light comes and goes
- Sensor B value jumps in live data
- Likely causes
- LikelyTerminal with weak contact tension in the sensor B plug
- PossibleHarness rubbing through intermittently under vibration
- PossibleCoolant crept into the connector
- RareSensor B element with unstable output
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €40 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.