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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.

  • Check engine light: Yes
  • Emissions related: Yes
  • Repair difficulty: medium

Common causes

Ordered by how often each turns out to be the cause.

  • Wiring or connector faultCommon
  • Air-assist actuator failedPossible

Parts involved

  • Air Assisted Injector
  • Wiring Harness
  • ECM

P2D51 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.