Technical Description of OBD-II Trouble Code
Low Input Bank 2 for Intake Air Temperature Sensor 1 Circuit
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code that is applicable to vehicles equipped with OBD-II. Although 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 increased combustion temperatures, it is important for the intake air tubing to 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 or a thermometer-like device. The thermistor receives 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-volt reference from the PCM, thereby informing the PCM about the temperature of the incoming air. If the PCM detects that the incoming air temperature sensor for bank 2 is unusually high, for example, 300 degrees, when the engine temperature is still relatively low, it will set a P00AC code. Bank 2 refers to the side of the engine that does not contain cylinder #1.
Related trouble codes for the IAT sensor circuit in bank 2:
Symptoms
A P00AC code may not exhibit any noticeable symptoms other than the illumination of the Malfunction Indicator Lamp (MIL). However, an emissions test may reveal higher Nox readings depending on the type of IAT failure. Additionally, the engine may experience pinging under load depending on the type of IAT failure.
Causes
Usually, the P00AC code is caused by a faulty IAT sensor in bank 2 (internally shorted, open, or otherwise damaged). However, it could also be caused by:
Possible Solutions
Connect a scan tool or code reader and check the IAT reading. With a cold engine, the IAT reading should roughly match the coolant reading since both readings reflect the ambient temperature. If the IAT #2 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 display the minimum value, around -20 degrees. If it does, then replace the IAT sensor #2.
However, if the reading is still high, unplug the sensor and check for 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 inspect and repair any short to ground on the signal circuit.
