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Home >> Geo >> 1992 >> Storm Base, 2D Hatchback, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Code Charts >> Code 23, Intake Air Temp (IAT) Sensor CKT, Low Temp Indicated >> Notes
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Code 23, Intake Air Temp (IAT) Sensor CKT, Low Temp Indicated: Notes

IAT sensor uses a thermistor to control signal voltage to ECM. ECM applies 4-6 volts on Blue/Black wire to sensor. When intake manifold air is cold, the sensor (thermistor) resistance is high and ECM senses a high voltage. As intake air warms, sensor resistance drops, and voltage drops.

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. This checks if Code 23 is due to a hard failure or an intermittent condition. Code 23 is set if engine is running longer than 2 minutes and signal voltage indicates IAT temperature is less than -22°F (-30°C).
  2. Simulates conditions for a Code 23 (high temperature indicated). If scan tester displays a high temperature, ECM and wiring are okay.
  3. Checks continuity of Blue/Black and Black wires. If Black wire is open, Code 21 may also be present.
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