OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P2AAB

Engine Coolant Bypass Valve B Position Sensor Circuit Intermittent/Erratic

The engine coolant bypass valve B position sensor signal drops out or jumps intermittently. Loose connector or noisy ground.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / numberA / AB

Possible causes

  • Sensor connector not seated high
  • Noisy ground reference medium
  • Connector with intermittent contact under vibration low

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 150–700 €
  • Estimated time: 0.5–3 h
  • Component: engine coolant bypass valve b position sensor
  • Component: wiring harness
  • Component: ecm
  • MIL / check engine light

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication