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Technical Description of OBD-II Trouble Code
Malfunction in Circuit 1 of Intake Air Temperature Sensor
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 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 located in the intake manifold. The sensor is supplied with a 5 volt reference wire (which also acts 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 results in higher resistance and higher signal voltage, while warmer air leads to 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 sensor, the P0110 code will be set.
Symptoms
There may not be any noticeable symptoms other than the illumination of the Malfunction Indicator Lamp (MIL). However, it is possible to experience poor drivability complaints.
Causes
Possible causes of the P0110 DTC include:
Possible Solutions
First, visually check that the IAT is properly in place and has not been dislodged. As a quick check of the IAT, use a scan tool to check for 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 in the readings (such as indicating an extreme temperature like -40 degrees or 300 degrees), then 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 refer to a repair manual for the specific 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), then 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, then there is a short to ground on the signal wire. If there is no continuity, then the PCM may be the problem.
2. If the KOEO IAT reading is at the low extreme, disconnect the IAT connector. Check that there is 5 volts on the signal wire and that the other wire is grounded.
a. If there is 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 wires together, there may be an open in the wiring harness or a problem with the PCM.
b. If there is no 5 volts present, check for reference voltage back at the PCM connector. If it is present at the PCM but not at the IAT sensor, repair the open in the signal wire.
Other DTCs related to the IAT sensor and circuit: P0095, P0096, P0097, P0098, P0099, P0111, P0112, P0113, P0114, P0127
Professional Service
While we always recommend resolving this issue through mechanical means, if that is not possible, we offer the option to permanently delete this specific DTC. All other codes will continue to be addressed. If you are interested in this option, please upload your ECU file to our portal.
