OBD Codes List

Diagnostic reference · P2AA7

P2AA7

Engine Coolant Bypass Valve B Position Sensor Circuit

System
Powertrain control (P code)
Lamp
Check Engine Light
Category
Powertrain - Fuel/Air Metering

What it means

P2AA7 means Engine Coolant Bypass Valve B Position Sensor Circuit.

Where it lives

For P2AA7, start at the sensor the description names.

Check these first

  • A failed coolant bypass valve B position sensor
  • An open or short in the bypass valve B position sensor wiring
  • A corroded bypass valve B position sensor connector
  • A coolant leak through the bypass valve B sensor housing

What to do next

  1. Scan all modules and read the bypass valve B position sensor voltage
  2. Inspect the bypass valve B sensor connector for corrosion or coolant intrusion
  3. Test the bypass valve B position sensor wiring for open and short faults
  4. Compare the bypass valve B sensor reading to a known good valve
  5. Replace the bypass valve B position sensor if the circuit is sound
  6. Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.