25 IAT Circuit - Temperature Out of Range High

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Description

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.

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Code Parameters

Code 25 will set if:

  • The ATS reading is over 125°C (257°F).
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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.
  • ATS temperature may be compared to CTS temperature with a Scan tool if engine has cooled overnight at ambient temperature. They should be within four degrees of each other with ignition On and engine Off
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