P0097 - INTAKE AIR TEMPERATURE SENSOR 2 CIRCUIT LOW INPUT

The Intake Air Temperature (IAT) sensor reads the temperature of the air entering the engine. Knowing this information is important because the greater the amount of intake of air, the higher the combustion temperatures. These combustion temperatures affect nitrogen oxide emissions by increasing them.

In order to prevent these high temperatures from causing combustion temperatures, it is necessary that the intake air pipe is intact, thus allowing air that is not in the engine compartment, fresh air, to enter the engine. The IAT sensor uses a thermistor or thermometer to measure the air temperature. This thermistor receives a 5-volt reference and ground signal. It should be noted that when the air temperature is cold, the resistance of the thermistor is high and the opposite occurs when the temperature is warmer.

This variation in resistance directly affects the reference voltage, which informs the PCM of the incoming air temperature. If the PCM detects that the temperature is high, but the engine temperature is actually low, the P0097 OBDII diagnostic code is set, in addition to illuminating the Check Engine light.

• Engine malfunction indicator lamp illuminated.
• The engine may be unstable on acceleration.
• The engine runs rich or lean depending on the outside temperature.

The factors for which the P0097 OBD2 fault code is stored are:

• Perhaps there is an open wire in the number 2 IAT Sensor harness preventing reference voltage.
• Maybe the intake air temperatures are excessively high.
• The IAT Sensor signal or ground circuit may be shorted.
• The Intake Air Temperature Sensor connector may be damaged.
• IAT Sensor 2 is faulty.
• Defective PCM.

To successfully diagnose and troubleshoot the problems associated with the DTC P0097 OBDII code you must do the following:

• With a scan tool, read the temperature of the IAT Sensor. If the engine is cold, the temperature reflected by the IAT Sensor should match that of the coolant. If as a result, you observe that the IAT has a higher reading, inspect the connector and check for damage. If no damage is found, disconnect the sensor and reinstall it. Re-measure and if -20 degrees, replace the sensor.
• If you get a high reading even after replacing the sensor, disconnect the sensor and check the resistance between the two wiring terminals. If you get infinite resistance, repair the short to the ground.