Technical Description of OBD-II Trouble Code
The input from the Intake Air Temperature Sensor 2 Circuit is registering as low.
What does that signify?
This diagnostic trouble code (DTC) is a standard powertrain code that applies to vehicles equipped with OBD-II. While it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
The IAT (intake air temperature) sensor is responsible for measuring the temperature of the air entering the engine. The intake air temperature is crucial because higher intake air temperatures lead to higher combustion temperatures. Increased combustion temperatures result in higher emissions of Nox (Nitrogen oxides).
To prevent these higher temperatures from causing further combustion temperature increases, the intake air tubing should be intact, allowing the engine to “breathe” air that is not sampled from the engine compartment. The IAT sensor measures air temperature using a thermistor, which is supplied with a 5-volt reference voltage from the PCM (powertrain control module) and a ground. Typically, when the air temperature is cold, the resistance in the thermistor is high, and when the air temperature is warmer, the resistance decreases.
This change in resistance alters the 5 V reference from the PCM, providing the PCM with information about the temperature of the incoming air. If the PCM detects that the incoming air temperature #2 is unusually high, such as 300 degrees, when the engine temperature is still relatively low, it will trigger a P0097 code.
Symptoms
There may be no noticeable symptoms of a P0097 code other than the Malfunction Indicator Lamp (MIL) illuminating. However, an emissions test may reveal higher Nox readings depending on the type of IAT failure. Alternatively, the engine may ping under load, depending on the type of IAT failure.
Causes
Usually, a bad #2 IAT sensor (internally shorted, open, or otherwise damaged) is the cause of a P0097 code. However, it could also be caused by:
Possible Solutions
Connect your scan tool or code reader and check the IAT reading. With a cold engine, the IAT reading should roughly match the coolant reading, as both will reflect the ambient temperature. If the IAT reading is excessively high, inspect the IAT connector for any damage. If no damage is found, unplug the IAT sensor and recheck the reading. It should now read the minimum, around -20 degrees. If it does, then replace the IAT sensor.
However, if the reading is still high, unplug the sensor and test the resistance across the two wiring harness terminals. If there is infinite resistance, then the PCM itself is faulty. If the resistance is not infinite, then check and repair any short to ground on the signal circuit.
Other DTCs related to the IAT sensor and circuit: P0095, P0096, P0098, P0099, P0110, P0111, P0112, P0113, P0114, P0127
