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

P2391

Diesel Intake Air Flow B Control Performance

Same as P2390 with the actuator electrically intact yet not delivering the commanded position - sticky valve, broken linkage, or position offset.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number3 / 91

Possible causes

  • Valve stuck due to soot high

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 200–1000 €
  • Estimated time: 1–4 h
  • Component: diesel intake air flow b
  • MIL / check engine light
  • emissions-relevant

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