Symptoms of a Bad Intake Air Temperature Sensor (IAT) – Replacement Cost

You know something is wrong when your car starts to produce unusual noises or just behave abnormally. Occasionally, your car might lose acceleration or produce a knocking sound.

There could be a lot of reasons for such problems, one of which is a bad intake air temperature sensor. An IAT sensor is crucial when starting the engine. It also measures the temperature of the air entering the engine.

Working

The engine computer or the ECU uses this information to guess air density and maintain balance in the mixture. It also performs many other forms of calculations to maintain engine functioning.

The PCM uses the information obtained from the IAT sensor in order to maintain the ratios in an air-fuel mixture inside the sensor. The principle of working is that the weight of the air depends on density.

The weight of cold air will be more than that of hot air, so cold air will require a larger amount of fuel for proper combustion. This information is provided to the ECU by the IAT sensor, which then makes the fuel injector inject the required amount of fuel for the type of air entering.

Location

The designation if an IAT sensor depends solely on the vehicle design. Different designs can incorporate the sensor in various places as per need.

You can look up for the position of the sensor in your vehicle on the internet or simply refer to the manual provided to you.

It can also be located on the left of the engine manifold or may be attached to the airflow sensor.

Diagnosis

If you think that the IAT sensor is the problem, the diagnosis is relatively easier. With some basic engineering tools at hand, you can easily diagnose the issue.

You just need to compare the experimental data with the values provided by the IAT sensor, and if they are not parallel, then the sensor is faulty.

In this article, we will learn some of the systems of a bad IAT senor.

Symptoms

Inadequate Power during Acceleration

When the sensor is not working properly, inappropriate signals are conveyed to the automated system (ECU), and incorrect proportions are obtained in the air-fuel mixture.

This leads to the engine not working to its full potential and less power available, rendering to bad acceleration. This problem is especially bad if you travel in hilly areas as acceleration requires a lot of power in such places.

This issue is also very serious if you have a sports car. Sports cars don’t have the margin for low power disposal during acceleration as speed is everything in a race, so it is avoided very strictly in such vehicles.

Less Fuel Efficiency

One of the most adverse effects of a bad IAT sensor is bad fuel efficiency. This is a very undesirable effect and results in a bad economy as well as the poor performance of your vehicle.

The reason for this defect is pretty much the same as that of the above. The sensor sends wrong signals to the ECU, and air/fuel proportions are not maintained in the mixture.

This results in a un-ideal condition where fuel does not give its maximum efficiency. To cater to this problem, the sensor needs to be replaced and, if not done timely, may result in further problems.

Cold Starts Issue

In cold conditions, starting up to become hectic and ECU initiates extra fuel deposition in the engine to meet up the requirement. The extra fuel provides extra heat energy while burning, and the engine starts.

The problem occurs when the IAT sensor is not properly working, so the ECU does not get to know about the cold air problem, which results in less fuel being transferred and engine not starting up.

In such conditions, you might know at first that what the problem is, so it would be wise to call a professional mechanic to look up for what the issue is. If the IAT sensor is the problem, you must have it changed at your earliest.

EGR Valve Problem

EGR stands for exhaust gas regulation. The EGR is a very important part of a car’s combustion system. It works by sending a small amount of exhaust gases back into the chamber to maintain a nominal temperature of the mixture.

When the EGR valve gets clogged up, it starts functioning appropriately. In some cars, the car system uses air temperature to control the EGR valve operation.

The symptoms of a bad EGR valve include stalling, fuel smell, increase in fuel consumption, knocking sound, and failure in smog tests. In such cases, the IAT sensor and the EGR valve both need to be changed.

Knocking Sound

Another reason for a faulty IAT sensor is a knocking sound produced in the engine. The sound is produced when there is less octane number in the fuel, and quality is decreased.

As a result, the pre-ignition of the fuel occurs in the chamber, which produces a knocking-like sound. This problem can also arise from a bad IAT sensor.

A bad sensor will obviously result in a bad proportion of the required components to avoid knocking. The air quality is judged badly, and the anti-knocking agent is not adequate.

In such cases, you should immediately have your IAT sensor changed as the fuel quality cannot be compromised.

Stalling Engine

A stall is referred to as a cease in operation. A stalling engine means that the engine stops working suddenly. This can be a very serious problem if you are on a highway with no station nearby.

This problem occurs when the engine is at low speeds, an interruption in fuel flow can result in the engine being ceased. It can result from a bad IAT sensor that may not send enough signals to the ECU, and the bad quality fuel supply can affect the engine badly.

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Engine Stumbling when Cold

This is another problem that arises when the IAT sensor is not working properly. During cold weather, the engine functioning is difficult as some parts can jam.

This results in more friction in internal parts, which means that the engine will consume more fuel.

If the sensor is not working properly, the ECU, which is working on air temperatures, will not send enough fuel and engine “stumbles” or hesitates in acceleration.

Black Smoke from the Engine

A problem that arises due to a bad sensor is black smoke ejecting from your car. This is due to the bad mixing of fuel with the air.

When the sensor does not work properly, the ECU will not signal the required proportion of the mixing, and the smoke turns black. This indicates the bad functioning and should be catered for in time.

Engine Overheating

When less power is provided during acceleration, the engine heats up and can even cease to function. This is due to a bad IAT sensor, which doesn’t tell the PCM about the actual air temperature, and it malfunctions.

This is a common problem and can be avoided by keeping the sensor in good condition. If the engine overheating is ignored, it can further result in a complete shutdown of your car, and it can be very troublesome in many cases.

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A sudden increase in revolutions after warming up

When the IAT sensor is not working properly, the engine starts to behave very much inappropriately, and it results in many issues.

One of the issues is abnormal changes in engine RPMs. Sometimes, when the IAT sensor is not working, the revolutions suddenly increase after the engine is warmed up, resulting in the engine being exhausted.

In these cases, the IAT sensor needs to be replaced in time so as to avoid any bad results.

Replacement of the IAT sensor

You cannot just readjust the sensor if the problem is associated with its physical functioning. However, if the problem is due to the clogging up of the sensor, you can clean it.

After cleaning, it will hopefully start working appropriately. You can use a good quality electronic cleaner spray as it gives a thorough cleaning effect.

IAT Sensor Replacement Cost

The average cost for a new IAT sensor is between $94 to $105. The average labor cost for this replacement is estimated to be between $39 to $50.

These are the general statistics, but they can vary greatly depending upon the scale of the shop you are having it repaired from and also the type of manufacturers from whom you are buying the parts.

Final Thoughts

I have tried my best to give you a detailed analysis of a bad IAT sensor. You must always remain vigilant and on the hunt for such symptoms so that you can make up for them.

It is a famous proverb that care is better than cure, so you should regularly clean the sensor to avoid clogging in the sensor, which is one of the reasons for its bad functioning.

If you encounter these symptoms and don’t have the required knowledge for the replacement or readjustment for the sensor, you must visit the nearest mechanic shop to have it checked.