P2AA9 — Engine Coolant Bypass Valve B Position Sensor Circuit Low
Voltage on the engine coolant bypass valve B position sensor signal line is below the expected window. Wire shorted to ground or sensor short.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Engine coolant bypass valve b position sensor
- Wiring harness
- Ecm
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
Diagnostic notes
- The malfunction indicator lamp may illuminate
Related codes
Sources
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.