P2AA7Engine Coolant Bypass Valve B Position Sensor Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Thermal management modules on modern engines use motor-driven rotary valves to split coolant between radiator, heater, oil or transmission cooler and engine block. A position sensor reports each valve's angle so the module can regulate it in closed loop. P2AA7 is the general circuit code for the sensor of valve B, used when the signal is unusable but cannot be classed as low (P2AA9) or high (P2AAA). No manufacturer documents P2AA7 publicly, and what valve B controls differs between makes. GM's 2025 diesel tables show how such a sensor is read on valve C: digitally over SENT, with readings outside a fixed count window filed as low or high faults after 4 seconds in 5, Type B. CARB counts these cooling actuators among the monitored components. Expect slow warm-up or temperature swings.
- What you may notice
- Malfunction indicator lamp on
- Slow warm-up or reduced cabin heating
- Fluctuating or elevated coolant temperature reading
- Likely causes
- LikelyLoose, corroded or coolant-wetted connector, or damaged sensor wiring
- PossibleLost 5 V supply or ground to the position sensor
- PossibleFailed position sensor inside the valve module
- RareFaulty sensor input in the engine control module
- 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.