Technical Description of OBD-II Trouble Code
Malfunction in the Circuit of Intake Air Temperature Sensor 2
What does that signify?
This diagnostic trouble code (DTC) is a standard 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 Intake Air Temperature (IAT) sensor is a thermistor that measures air temperature by detecting resistance in the air. It is typically located in the intake air ductwork, but in some cases, it may be found in the intake manifold. The sensor is supplied with a 5 volt reference wire (which also serves as a signal wire) from the Powertrain Control Module (PCM) and a ground wire.
As air flows over the sensor, the resistance changes, which in turn affects the 5 volts supplied to the sensor. Colder air leads to higher resistance and higher signal voltage, while warmer air results in lower resistance and lower signal voltage. The PCM monitors this voltage change and calculates the air temperature. If the PCM detects a voltage that is outside the normal operating range for the #2 sensor, the P0095 code will be triggered.
Symptoms
There may not be any noticeable symptoms other than the illumination of the Malfunction Indicator Lamp (MIL). However, it is possible to experience complaints of poor drivability.
Causes
Potential causes of the P0095 DTC include:
Possible Solutions
First, visually check that the IAT is properly positioned and has not been dislodged. As a quick check of the IAT, use a scan tool to check the IAT reading with the Key On Engine Off (KOEO). If the engine is cold, the IAT reading should be the same as the Coolant Temperature Sensor (CTS) reading. If there is a significant variance (for example, if it indicates an extreme temperature like negative 40 degrees or 300 degrees), there is likely a problem. Unplug the IAT and perform a resistance test across the two terminals.
Each sensor will have different resistance values, so you will need to refer to a repair manual for that information. If the resistance of the IAT sensor is not within specifications, replace the sensor. There should be some resistance, so if it measures infinite resistance, replace the sensor.
If the issue persists, here is some additional diagnostic information:
1. If the KOEO IAT reading is at the high extreme, such as 300 degrees (which is obviously inaccurate), disconnect the IAT sensor. If the reading now shows the lowest extreme (around -50 degrees), replace the IAT sensor. However, if unplugging the IAT does not change the reading, turn off the ignition and disconnect the PCM connector. Use a voltmeter to check for continuity between a good ground and the signal wire to the IAT. If there is continuity, repair the short to ground on the signal wire. If there is no continuity, there may be a problem with the PCM.
2. If the KOEO IAT reading is at the low extreme, again disconnect the IAT connector. Check that there is 5 volts on the signal wire and that the other wire is grounded.
a. If you have 5 volts present and a good ground, jumper the two terminals together. The reading on the scanner should now be at the high extreme. If it is, replace the IAT sensor. However, if the reading remains low even after jumpering the two wires together, there may be an open in the wiring harness or a problem with the PCM.
b. If you do not have 5 volts present, check for reference voltage back at the PCM connector. If it is present there but not at the IAT sensor, repair the open in the signal wire.
Other trouble codes related to the IAT sensor and circuit: P0096, P0097, P0098, P0099, P0110, P0111, P0112, P0113, P0114, P0127
