Circuit DescriptionThe intake manifold air temperature sensor monitors intake manifold air temperature and passes information to the electronic control. The intake manifold 1 temperature sensor is a variable resistor sensor and is used to measure the temperature of the air entering the intake manifold of the engine. The electronic control module (ECM) supplies 5 volts to the intake manifold temperature SIGNAL circuit. The ECM monitors the change in voltage caused by changes in the resistance of the sensor to determine the intake manifold temperature.

When the intake air is cold, the sensor or thermistor resistance is high. The ECM signal voltage only pulls down a small amount through the sensor to a ground. Therefore, the ECM senses a high signal voltage or low temperature. When the intake air is warm, the sensor resistance is low. The signal voltage pulls down a large amount. Therefore, the ECM senses a low signal voltage, or a high temperature. This fault code indicates that the intake manifold temperature has exceeded the maximum engine protection limit.

Component LocationThe intake manifold temperature sensor 1 is located in intake manifold 1.

Conditions for Running the DiagnosticsThe first part of the diagnostic runs continuously while the keyswitch is in the ON posistion or the engine is running.Conditions for Setting the Fault CodesThe Engine Control Module (ECM) detected the intake manifold temperature was greater than a calibrated threshold.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.The torque output of the engine will be reduced.Conditions for Clearing the Fault CodeTo validate the repair, start the engine and let it idle for 1 minute.The fault code status displayed by INSITE™ electronic service tool will change to inactive and the torque derate will be removed immediately after the intake manifold temperature falls below a calibratible limit set in the ECM and the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp and/or MIL immediately after the diagnostic runs and passes.The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults.

Shop TalkThe intake manifold 1 temperature sensor measures the temperature of the charge-air as it passes through the intake manifold. Possible causes of this fault code include.

Plugged charge-air cooler finsRestricted airflow through the charge-air coolerUndersized charge-air coolerHigh turbocharger compressor outlet temperature.

Possible Cause:1) Intake Manifold temperature sensor failure2) ECM calibration