Do you notice a sudden drop in engine power, increased fuel consumption, and difficult cold starts?

The faulty intake air temperature sensor could be the culprit for all this.

A faulty IAT sensor sends wrong voltage signals to the engine control unit that affects the air/fuel mixture formation which results in the malfunctioning of various parts in the vehicle.

In this article, we will make you understand what mechanism works behind this small but important component and the signs that indicate you of the failing IAT sensor and how to diagnose it before it becomes a serious problem for your vehicle.

Symptoms of A Bad Intake Air Temperature Sensor

1. Drop in Engine Power During Acceleration

A defected IAT sensor sends wrong or inappropriate signals to the engine control unit that causes imbalanced ratio of air and fuel mixture. This leads to a massive decrease in engine power which ultimately slows down the acceleration. So if you notice slow acceleration, this means the IAT sensor may have some issues with it.

However, there are other reasons also for decreased acceleration therefore you should approach a professional mechanic who can exactly identify the problem.

2. Decrease in Fuel Efficiency

Another noticeable symptom of a faulty IAT Sensor is a significant decrease in fuel efficiency. As said earlier, a faulty IAT sensor sends wrong data to the engine control unit and this data affects the calculations which results into a decrease in fuel efficiency. In other words, inappropriate formation of air/fuel mixture doesn’t allow the engine to drive maximum fuel efficiency.

If the temperature of the air/fuel mixture would be extremely low, it would require more oil because the cool air is denser and due to high density, the ECU will request more oil to bring the balance between air and fuel.

3. Difficult Cold Start

If you face difficulty in starting the engine in cold conditions, the defective IAT sensor could be the reason for it. In cold conditions, the engine requires additional fuel for combustion. The IAT sensor sends signals to the ECU, with those signals the ECU comes to know that additional fuel is required.

But a faulty IAT sensor sends wrong signals due to that the ECU is not able to know the additional fuel requirement which results in the decreased transmission of fuel.

And it further causes difficulty in starting the engine.

4. Check Engine Light Turns On

When the IAT sensor becomes faulty, the ECU may turn on the check engine light. So if you notice check engine light is on that could be due to defected IAT sensor.

However, there are a number of reasons that cause illumination of check engine light, therefore, you should approach an expert mechanic for detailed and correct inspection.

Related Article: How to Reset Check Engine Light

5. Engine Stalling, Stumbling, and Rough Idling

The engine stalling, frequent stumbling, and poor idling are associated with an improper supply of fuel. And a defective IAT sensor causes an insufficient supply of fuel that results in these symptoms which may become a serious concern for your vehicle.

What is an Intake Air Temperature Sensor

The intake air temperature sensor measures the temperature of the air entering the engine. The engine control unit uses this information to know the air density.

According to the air density, the ECU sends request for fuel supply to maintain the balance of air/fuel in its mixture for optimal combustion. The cold air is denser than hot air and it requires more fuel to balance the same air/fuel mixture.

What is the function of the Intake Air Temperature Sensor

The intake air temperature sensor is also known as the air charge temperature sensor has three parts – sensor element, sensor body, and connector. The sensor element is a thermistor that measures temperature by detecting resistance in the air. The sensor body provides mounting to both the sensor element and the connector and further, the connector connects the sensor element to the ECU.

When air passes through the sensing module of IAT sensor then due to temperature, the thermister in the sensing element will change its resistance. The resistance will go up and down on changing the temperature.

If the temperature increases, the resistance will decrease and if the temperature decreases, the resistance will get increased. And through this, the ECU will know the temperature of the air which will be utilized in ensuring balanced air/fuel mixture.

Diagnostic Trouble Code (DTC) for Intake Air Temperature Sensor (IAT)

There is a number of diagnostic trouble codes associated with intake air temperature sensor that indicates towards a specific issue with the IAT sensor.

Before we find more about trouble codes, it is essential to know, how we can find the trouble codes.

If you see check engine light is on. This means something is wrong with your vehicle that has caused the check engine light to turn on. Now, plug in a scan tool or code reader into the 16-pin OBD II diagnostic connector that is generally located under the dash. This code reader will show you the code that has turned on the check engine light.

Let’s dig the information about some important diagnostic trouble codes for IAT sensor in detail.

P0110 Trouble Code

P0110 is a general code that indicates to the problem of intake air temperature sensor circuit malfunction. In other words, this code appears when the IAT sensor sends incorrect voltage input signals to the engine control unit that causes the ECU to supply incorrect amount of fuel for combustion. This results into excessive fuel consumption, poor power, and difficult cold start.

P0113 Trouble Code

P0113 code refers to the intake air temperature sensor circuit high input problem. It means when the IAT sensor output voltage is more than 4.91V for 0.5 seconds or more, the engine control unit comes to result that the IAT sensor has an open circuit. In this condition, if you continue to drive vehicle for an extended time can cause internal problem with rings and valves.

P0112 Trouble Code

This code is for intake air temperature sensor circuit low input problem. It means when the engine control unit receives extremely low voltage from IAT sensor due to wiring issue or a failed IAT sensor, the ECU sets the P0112 trouble code. Driving the vehicle with this trouble code can lead to ignition problem.

P0111 Trouble Code

The trouble code P0111 is for the intake air temperature sensor circuit range problem. It means the engine control unit has received the IAT sensor input out of the sensor range. In this case, the IAT sensor range input can go either too low or too high that results in a short circuit or open circuit.

This problem leads to hard start issues and excessive fuel consumption.

The location of the IAT sensor in vehicles varies. In older vehicles, it is found near the air filter. In some vehicles, it can be located in the intake air tube that is placed between the air filter and the throttle body. While in newer vehicles, it can be located in the intake manifold near the throttle valve housing or integrated into the MAF sensor.

However, the best way to locate the IAT sensor is to refer the manufacturer’s manual to avoid any sort of confusion.

Intake Air Temperature Sensor Replacement

When it comes to replacement of IAT sensor, it is recommended to clean the IAT sensor first, sometimes, even merely cleaning the sensor is enough to bring it back to working condition. To clean the sensor, remove it from the intake manifold. And then spray on the clogged area with an electric cleaner. If after cleaning the sensor, still, it doesn’t work then consider replacing the sensor.

How to Replace a New Intake Air Temperature Sensor

Replacing the intake air temperature sensor is pretty simple. If you have little knowledge and a few basic tools including protective gloves, safety glasses, and a new IAT sensor, you can replace the IAT sensor on your own.

But if you’re not confident, it’s better you hire a certified mechanic for this job because while replacing the IAT sensor, you have to deal with some very high temperatures that can be dangerous for you if you don’t know how to deal with them. The professional mechanics have all the tools and tricks to deal with this situation.

The replacement process includes:

  • Removal of the defected IAT sensor
  • Installation of the new IAT sensor

Let’s begin the replacement process.

Removal of the defected IAT sensor

  1. Locate the IAT sensor which is generally located in the intake manifold or the air cleaner housing. In some vehicles, it is also integrated into MAF sensor.

  2. Disconnect the negative terminal of the battery.

  3. Remove the electrical connector.

  4. Remove the sensor either by pulling it straight out or unscrewing it with a wrench.

Installation of the new IAT sensor

  1. Install the new sensor either by pushing it straight in or screwing it with a wrench.
  2. Reconnect the electrical connector.
  3. Reconnect the negative terminal of the battery as the last step. And the IAT sensor is ready for optimum performance.

Intake Air Temperature Sensor Cost

The average cost for the intake air temperature sensor comes between $100 and $150. However, you can cut the cost by comparing prices from different brands. The labor cost can go up to $80 to $120. Hence, the total amount you would pay for the IAT sensor replacement can go up to $270. The total cost also depends on the type of vehicle you have and how much work is required for the replacement.

In Conclusion

In last words, I would only say that don’t underestimate the important role of the IAT sensor that can affect the vehicle’s engine performance. If there is any minor symptom of failing IAT sensor then have a professional mechanic for detailed inspection of the vehicle and if it requires, go for the replacement of the IAT sensor to avoid other repair costs associated with it.