P0111 moderate

Intake Air Temperature Sensor 1 Circuit Range/Performance

What does P0111 mean?

The P0111 code means the vehicle's onboard diagnostic system has detected: Intake Air Temperature Sensor 1 Circuit Range/Performance. This is a moderate severity code.

Common Symptoms

  • Check Engine Light on
  • Slightly rough cold starts
  • Minor fuel economy reduction
  • No major drivability issues

Probable Causes (Ranked by Likelihood)

  • IAT sensor reading does not correlate with coolant temp on cold start Very High
  • Partially failed sensor giving erratic readings High
  • IAT sensor located in a heat-soak area Moderate
  • Wiring intermittent fault Moderate

Step-by-Step Diagnostic Procedure

  1. After a cold soak, compare IAT and ECT readings at startup. Both should be within 10-15 degrees F of ambient temperature.

  2. Monitor IAT during a test drive. It should rise moderately as intake duct heats up.

  3. An IAT reading that does not change during driving or is fixed at an extreme value indicates sensor failure.

  4. Replace IAT sensor if readings are erratic or unresponsive.

Frequently Asked Questions

Will P0111 affect my fuel mileage?

Slightly. If the IAT reads too cold, the ECU may over-enrich the mixture. If too hot, it may lean it out. The effect is usually minor unless the reading is at an extreme value.

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