1992 Geo Tracker LSi, AutomaticFACTORY OEM SERVICE PROCEDURE

Code 25, Intake Air Temp Sensor CKT, High Temp Indicated: Notes

IAT sensor uses a thermistor to control signal voltage to ECM. ECM applies 4-6 volts on Red/Black wire to the sensor. When intake air is cold, sensor resistance is high. ECM will sense high signal voltage. As intake air temperature warms, sensor resistance decreases and voltage drops.

NOTE: Test number refers to number on diagnostic chart.
  1. Simulates Code 23. If ECM stores Code 23, ECM and its wiring are okay, and IAT sensor is faulty. If Code 25 resets, IAT sensor is okay. Check for faulty wiring to ECM or a faulty ECM.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

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