23 IAT Circuit - Temperature Out of Range Low

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The air temperature sensor (ATS) is a thermistor located in the air intake passage of the air induction system on the engine. When the sensor is cold it has a high resistance, the resistance decreases as the temperature of the sensor increases. The PCM supplies a five volt signal to the sensor which is also connected to ground. The PCM reads the voltage drop on the sensor signal line to determine air temperature.

Code Parameters

Code 23 will set if:

  • The PCM sees ATS temperature less than -30°C

Diagnostic Aids

  • Refer to Temperature vs. Resistance chart.
  • When attempting to diagnose an intermittent problem. use the Scan Tool to review supplemental diagnostic information.
    • The supplemental data can be used to duplicate a problem. Select MALF History from Scan Tool EC menu.
  • Check the tightness of the female terminal grip with a spare male terminal.
  • This code may be set if the vehicle has been in extremely cold ambients. Ask the customer if this has occurred.
  • Code 23 will set if the ATS is disconnected and the ignition is cycled on.
  • ATS may be compared to CTS temperature, with a Scan Tool, if engine has been cooled overnight at ambient temperature. They should be within four degrees of each other with ignition On and engine Off