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Symptoms of a Bad Intake Air Temperature Sensor (IAT)

intake air temperature sensor

Have you ever noticed your car’s engine making a knocking sound? Or noticed a drop in acceleration? Chances are that your car’s Intake Air Temperature Sensor (IAT) is damaged and should be fixed immediately to avoid any serious hard to the engine. In this article, we will discuss the symptoms of a bad Intake Air Temperature Sensor and how you can avoid the problems associated with IAT sensor.


What is an Air Temperature Sensor (IAT)?

Different Names for the Same Component:

An Air Intake Temperature Sensor (IAT) is known by many names according to different manufacturers. General Motor calls it manifold air temperature (MAT), while Ford calls it vane air temperature (VAT) or air charge temperature (ACT). Those manufactured by Chrysler are called charge temperature sensors (CTS) while Bosch calls them air temperature sensors (ATS).


Function of Air Temperature Sensor (IAT):

An air temperature sensor monitors the temperature of the air that is entering the engine. This information is required by the engine computer to estimate air density so that it can balance the air and fuel mixture properly for efficient combustion. Since cold air has a higher density compared to hot air, the former requires more fuel to maintain the ideal air/fuel ratio.


How does it work?

The Air Temperature Sensor (IAT) works the same way as the Coolant sensor. The sensor is a thermistor and its electrical resistance changes according to the temperature. It is located on the intake manifold and the tip is exposed to observe the air entering the engine.


Symptoms Indicating a Problem with IAT Sensor

When the IAT sensor fails or gets damaged, it displays some symptoms through which the driver can easily conclude that the problem is with the specific component.

Drop in Acceleration

Due to a faulty sensor, the PCM may think that the air outside is cold or warm than it actually is. A false signal may cause the PCM to miscalculate the air and fuel mixture resulting in a drop in acceleration.

Hard Cold Start Condition

Some engines rely on a signal from IAT sensor to initiate the cold start injector. If the sensor sends wrong information, the cold start injector might not work resulting in a hard cold start.

EGR Valve Affected

In some cars, the PCM uses air temperature to control the operation of EGR Valve. Due to a faulty IAT sensor, the function of EGR valve can be affected too.

Poor Fool Economy

In normal condition, the engine computer makes a constant adjustment in the fuel and air level mixture to ensure maximum fuel efficiency. The computer relies on the information from IAT sensor and if a false signal is sent, the fuel efficiency decreases significantly.

Diagnostic Trouble Code Associated with IAT

A damaged Intake Air Temperature Sensor usually triggers two trouble codes: P0112 or P0113.
The P0112 code indicates that the IAT sensor is operating at a low voltage and reporting a temperature of about 300 °F (149 °C).
The P0113 code is caused by a high circuit voltage and means that the IAT sensor is reporting a temperature of about -38 °F (-39 °C).


Diagnosing the Air Temperature Sensor

To quickly check the air temperature sensor for any issue, you can use the OBD2 scan tool and compare the air temperature reading with the coolant temperature reading once the engine is warm. The air temperature sensor should have a reading less than the coolant sensor. If you do not have a OBD2 scan tool, you can check out our obd2 scanner reviews to find one that suits you for a good price. The review is here: OBD2 scanner review


IAT Sensor Replacement or Adjustment

Since the Air Temperature Sensor is a solid-state component, it cannot be adjusted. However, you can clean the sensor if it is dirty or clogged and it will be in a good working condition again. To clean the sensor, remove it from the intake manifold then use an electronic cleaner to spray the affected area. Avoid using any other type of cleaner as it can damage other components or the plastic housing.

Installing a New Air Temperature Sensor

Installing a new IAT sensor is fairly simple and requires some basic tools including a pair of gloves, new IAT sensor, and safety glasses.

Step 1:
Start with locating the IAT sensor which can be found in the air intake boot or intake manifold.

Step 2:
Disconnect the negative terminal of the battery.

Step 3:
Inspect the IAT sensor and remove its electrical connector.

Step 4:
Remove the IAT sensor by either pulling it straight or unscrewing it.

Step 5:
Install the new IAT sensor

Step 6:
Reconnect the electrical connector and the battery terminal.


Replacement Cost

If you find it difficult to replace the IAT sensor yourself, take your car to a professional mechanic. The average cost of replacement is between $53 and $134. The price of the component varies between $30 and $70, whereas the labour cost can be approximately $25 to $60.

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