P2AAAEngine Coolant Bypass Valve B Position Sensor Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- With P2AAA the position sensor of coolant valve B reports a value above anything a working sensor would deliver. Typical reasons are a signal line touching a supply wire, a damaged output stage inside the sensor or, depending on how the input is wired, an interrupted ground. Since the engine computer can no longer tell where the valve really stands, it loses closed-loop control and has to rely on a fixed default position. No manufacturer documents P2AAA publicly. GM's code for the comparable valve C, P23C5, flags a SENT value above 4,050 counts, again over 4 of 5 seconds and as Type B, and names a short to power as the cause. CARB requires input components to be checked for wiring faults and for readings beyond their limits. P2AA9 is the low counterpart, P2AAB the sporadic one.
- What you may notice
- Check engine light on
- Coolant temperature swings or stays off target
- Possibly reduced engine power if the module protects against overheating
- Likely causes
- LikelySignal wire in contact with a supply or reference voltage wire
- PossibleSensor ground open at the connector or splice
- PossiblePosition sensor in the valve module defective
- 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 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.