intake air temperature sensor

Intake Air Temperature Sensor Symptoms, Function & Location (IAT)

In Engine by Josh S3 Comments

intake air temperature sensorDid you notice 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.

The air intake temperature sensor or the IAT sensor is among the most important sensors associated with the control unit of your engine system. There are various reasons due to which the air intake temperature sensor can go bad. The most common reason for the failure of the IAT sensor is damage to the sensor that occurs because of backfiring of the engine.

Contamination and the accumulation of dirt, dust, carbon, and oil can also result in faulty and inaccurate readings and the sensor may transmit the wrong signals to the engine control unit. As the vehicle ages, the air intake temperature sensor can also be subjected to wearing and tearing.

Further, in case of accidents, raining or flooding if the water gets into the internal components of your vehicle, it can result in reduced efficiency or complete failure of the sensors. Apart from these reasons, the air intake temperature sensor can also show wrong readings because of the damage to the wires and electrical connections, loose wiring and the loose connection to the air filter unit. By replacing the IAT sensor that has gone bad, you will improve the fuel efficiency of your vehicle as well as the overall engine performance. It will also protect you from spending extra costs that are associated with the bad IAT sensor.


iat sensorWhat is an Intake air temperature sensor?

The Intake air temperature sensor or IAT sensor has the core function of monitoring the temperature of the air that is entering the engine of your vehicle. This information is very useful for the engine control unit or ECU for many functions and calculations, such as calculating the air density for effective ignition timing and fuel efficiency. The computer system of your engine or the PCM requires this information in order to stabilize and regulate the air-fuel ratio for the combustion engine. As a result, it ensures optimum combustion and efficient fuel consumptions.

The principal science behind evaluating these sensed readings is that the hotter hair is lighter than the colder air in density, therefore the cooler air would need relatively more fuel in order to burn with the fuel that is injected in the engine. If the air and fuel mixture ratio is not proper, the vehicle will not perform to its full capacity and the fuel consumption may also be increased.

With this information, the computer system of the vehicle automatically regulates the fuel injection by altering the injection pulse to inject more fuel when required. it is especially important to maintain the proper air-fuel ratio during the hot winds of summer as well as the cool nights of winter as the temperature extremes can greatly affect the performance of your vehicle by changing the density of the air that is entering the vehicle. It is also very helpful in maintaining the emission levels of your vehicle.


Intake Air Temperature Sensor Symptoms (IAT)

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. First you will find a troubleshooting table, further down you will find more information.

Bad Intake Air Temperature SensorDrop in Acceleration

Hard Cold Start Condition

EGR Valve Affected

Poor Fool Economy

Check Engine Light ON
Faulty Intake Air Temperature Sensor

Faulty MAF(If integrated)

Faulty wirings to IAT Sensor

Bad connection in plug to IAT sensor

Faulty ECM
Replace IAT Sensor

Replace MAF Sensor (If integrated)

Repair Wirings to IAT Sensor

Clean connector plug to IAT Sensor

Replace ECM

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 the 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 the 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 engine control unit relies on the information from the 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).


Where is the IAT sensor located?

The location of the Intake air temperature sensor is an easily arguable subject due to different locations in a variety of designs. The best way to locate the IAT sensor in your vehicle if to refer to the service manual that is provided by your manufacturer. The Intake Air Temperature (IAT) sensor of your vehicle is usually installed in the lefthand side of the intake manifold. It could be on the throttle body attached right to the intake manifold.


iat sensor diagnosticsDiagnosing a bad or failed air intake temperature sensor

The diagnostic procedure of checking if the IAT sensor has gone bad is relatively easier and you can do it yourself if you have some basic knowledge and the tools available to you. You will usually require a multimeter, a scanning tool, wire piercing probe and some tools to reach it. it is better if you test and diagnose the problem before attempting to replace the IAT sensor. Here is a quick step by step guide that you can follow to diagnosing a bad IAT sensor.

  1. Keep the service manual of your vehicle with you
  2. Locate the sensor and clear the area
  3. Connect the scanning tool to the vehicle and turn on the engine
  4. Record the temperature of the IAT sensor. Typically the temperature readings should be 10 degrees Fahrenheit more or less than the vehicle’s ambient temperature.
  5. If the readings are not proper, there could be a problem with your IAT sensor.
  6. Shake the connection of the mass air flow sensor to the IAT sensor
  7. Make sure that the connections are proper and wiring is in good condition
  8. Check once again if the readings are fixed
  9. If the readings change, the connection may not be in good condition
  10. Match the code that is shown to the code reference in your service manual
  11. If the temperature is 300 degrees, check the wires of the MAF sensor as they can be damaged.
  12. Remove those damaged wires and try again. If the readings are not fixed you may need to replace the connector.
  13. Test the IAT sensor with a multimeter on ohms
  14. If the resistance is between 0 to 47 ohms, the IAT sensor is faulty.


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.


IAT sensor replacement cost

The average replacement cost of IAT sensor comes between $60 and $110. The labour cost is between $20 and $70, while the parts itself cost between $100 and $150.
The cost of IAT sensor replacement can vary greatly depending on the type and the manufacturer of your vehicle when you are buying the parts. On average for most vehicles, you will have to pay a sum of $163 for the replacement of an Intake air temperature sensor.

The price range for most vehicles on average is between $80 to as much as $270. For some vehicles, you can get the replacing part for as low as $7 while all the other added cost or around $100 to $150 would be for the mechanic and labor cost. This greatly varies with the mechanic you are dealing with. By doing it yourself following an easy to replace guide you can save up on all the labor cost involved in it.

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    1. Author


      It could, but it’s most likely something else like the throttle body or the crankshaft sensor. Also if the car is running very rich, it could be the problem. Read the trouble codes if possible if you havn’t yet!

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