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P009A

Intake Air Temperature/Ambient Air Temperature Correlation

Intake air temperature and ambient air temperature readings deviate beyond plausible limits — at engine off both should match within tolerance.

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

Common causes

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

  • One sensor driftedCommon

Parts involved

  • IAT Sensor
  • Ambient Air Temp Sensor

P009A 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.