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

P2D51

Air Assisted Injector Control Circuit

The control circuit of the air-assisted fuel injector reports a generic fault. Air-assist atomization for cold-start or low-load conditions cannot be commanded.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / numberD / 51

Possible causes

  • Wiring or connector fault high
  • Air-assist actuator failed medium

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 200–1200 €
  • Estimated time: 1–5 h
  • Component: air assisted injector
  • Component: wiring harness
  • Component: ecm
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required

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