Intake And Maf Sensor

Intake Air Temperature Sensor (IAT) Symptoms, Location & Replacement Cost

In Engine by 22 Comments

Have you noticed your car’s engine drop in acceleration lately?

The chances are that your car’s intake air temperature sensor (IAT) is damaged and that it should be fixed immediately to avoid any serious damage to the engine.

In this article, you will learn the symptoms and the meanings of a bad intake air temperature sensor. Let’s begin with the symptoms.

7 Bad Air Intake Temperature Sensor Symptoms

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

The most common symptoms of a bad intake air temperature sensor are check engine light, rough idle, bad engine performance, and changed fuel consumption.

Here is a more detailed list of the 7 most common symptoms of a bad intake air temperature sensor.

1. Check Engine Light

Check Engine Light

The first thing you may notice when it comes to a bad intake temperature sensor is a check engine light on your dashboard. The engine control unit heavily monitors all sensors in a car engine, and if one fails, it will light up the check engine light immediately.

If you notice a check engine light on your dashboard, you should check the trouble codes with an OBD2 scanner or let your mechanic do it.

2. Drop in Acceleration

Slow Car Acceleration

Due to a faulty intake temperature sensor, the engine control module may think that the engine’s air is colder or warmer than it actually is. A false signal may cause the PCM to miscalculate the air and fuel mixture, resulting in a drop in acceleration.

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Colder temperatures require more fuel, which the engine control module is programmed to calculate.

3. Hard Cold Start Condition

Hard Starting

The starting condition is a very critical moment for your car. This is the time when your car needs a lot of and the correct amount of fuel.

If your intake temperature sensor makes the engine control unit inject the wrong amount of fuel, you might find it a tough time trying to start your car.

4. Rough Idle

Car Engine Rough Idle

Idle is also one of these conditions when the engine is susceptible to the right air-fuel mixture. This is also a condition when you can feel the faulty air intake temperature sensor’s slightly faulty air-fuel mixture.

If you experience some small hiccups on idle, it can be a faulty IAT sensor.

5. Misfires

Misfiring Engine E1609865653850

Misfires occur when the combustion inside the engine cylinder fails. This can be caused by either a faulty spark or a wrong air-fuel mixture.

You can feel misfires as hiccups or interruptions while you accelerate. If you can feel this on acceleration, there may be a problem with your IAT sensor.

6. EGR Valve Affected

Egr Valve Engine

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

An EGR valve that does not function properly can cause a lot of strange symptoms in your car.

7. Poor Fuel Economy

Bad Fuel Consumption

In normal conditions, the engine computer constantly adjusts the fuel and air level mixture to ensure maximum fuel efficiency.

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The engine control unit relies on the IAT sensor’s information, and if a false signal is sent, the fuel efficiency decreases or increases significantly.

If you notice a different fuel consumption than normal, it can be because of a failed IAT sensor.

What is an Intake Air Temperature Sensor?

Intake Temperature Sensor

The intake air temperature sensor or IAT sensor has the core function of monitoring the air temperature that is entering the engine of your vehicle.

This information is beneficial 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 to stabilize and regulate the combustion engine’s air-fuel ratio. As a result, it ensures optimum combustion and efficient fuel consumption.

Where Is the IAT Sensor Located?

Mass Intake Air Temperature Sensor

The Intake Air Temperature Sensor is located somewhere on your intake pipes between the air filter and the intake manifold. It is often integrated with the MAF Sensor.

In many cases, it is also installed on the intake manifold.

The intake air temperature sensor’s location is not standard due to different locations in a variety of designs. The best way to locate the IAT sensor in your vehicle is to refer to the service manual that is provided by your manufacturer.

Intake Temperature Sensor Diagnostics

Car Diagnostics

The diagnostic procedure of checking if the IAT sensor has failed is relatively easy. You can do it yourself if you have some basic knowledge and the tools available to you. Be sure to have a repair manual for your car ready.

  1. Connect the OBD2 scanner to your car. Turn on the engine.
  2. Check the live data and check the temperature of the IAT sensor. Typically, the temperature readings should be 10 degrees more or less than the vehicle’s ambient temperature, depending on the outside temperature and the engine’s temperature.
  3. If the readings are not realistic, there could be a problem with your IAT sensor or the wirings to it. If the temperature is over 300 degrees or has a low unrealistic value, check the MAF sensor/IAT wires as they can be damaged.
  4. Ohm-measure the Intake temperature sensor and make sure they are the same as your repair manual suggests. If you can find that the ohms are not correct, replace the sensor and remove the trouble codes.
  5. If the sensor seems correct, check and measure the sensor’s wirings and the engine control unit.
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IAT Sensor Replacement Cost

An intake temperature sensor costs 20$ to 150$, and the labor costs 20$ to 100$. You can expect a total of 40$ to 250$ for an intake temperature sensor replacement.

If your intake temperature sensor is integrated into the MAF sensor, the part cost can increase rapidly. Some MAF sensors cost up to 400$.

The replacement of a MAF sensor or intake temperature sensor is often very straightforward and can often be made yourself with basic knowledge.

In some cars the IAT sensor can be located under the manifold in a difficult location, but this is quite rare.

22 thoughts on “ Intake Air Temperature Sensor (IAT) Symptoms, Location & Replacement Cost ”

Comments
    1. Author

      @Phillip

      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!

      1. Please I drive a Honda odyssey 1997 model. Can’t seem to locate where the IAT sensor is. Anyone with a clue to help out?.

    2. I have a 2000 Toyota Land Cruiser 105series FZJ PETROL I am not sure how many sensors are on the air filter box and is it meant to have an air flow meter I’m confused and need to figure it out as I am positive it has something to do with the air filter box components

    1. Author

      @Misbahy

      It’s most likely the “Idle control valve” (or throttle body if you don’t have an idle control valve). Clean the throttle body or the idle control valve and try again.

  1. When plugged into my obd2 scanner and reading the live data, the IAT Sensor Temperature reading never goes much above what the outside temperature is. So even after ~15 minutes of driving my IAT sensor reads 59 degrees Fahrenheit, but my engine coolant temperature is at 165. From my understanding, some of the ambient engine heat should be affecting what the IAT sensor reads, correct? Thus the IAT sensor reading should be at least somewhat closer to the Engine Coolant Temp than a measly 59 degrees which is almost the same as the outside temperature. I have a 2006 Audi A3. I would test the IAT sensor but don’t own a DMM. I’ve read the live data twice, once on a 17 minute drive at freeway speeds, and another 15 minute drive at city speeds. Both times the live data readout only showed the IAT maybe a few degrees above the outside temperature. The scanner has no codes regarding the IAT sensor/circuit. Short Term Fuel Trim and Long Term Fuel trim for Bank 2 both were both pegged at +25% which means a lean condition in Bank 2. I’m not a car guy and all of this is new to me, I’m thinking I have a bad IAT and a maybe a vacuum leak somewhere on bank 2? My car idles rough sometimes, has decreased fuel mileage, and occasionally I can smell raw unburnt gas outside the vehicle while idling. I’m not a car guy and all of this obd data is new to me so any insight is appreciated.
    Codes my car has pulled collectively over the past couple months. Never did these codes occur all at once.
    P2099 – Post Catalyst Fuel Trim System Too Rich Bank 2
    P2198 Oxygen Sensor Signal Biased / Stuck Rich Bank 2 Sensor 1
    P2273 Oxygen Sensor Signal Biased / Stuck rich Bank 2 Sensor 2
    P0174 – Bank 2 System Too Lean

    1. Author

      @Wish I Was Mechanic
      In this scenario, it seems like your IAT is fine. With these codes, I would absolutely start looking for any vacuum leaks around the intake. What engine do you have? Seems pretty strange with an Audi A3 with 2 banks. VR5 engine? Check for vacuum leaks or any broken PCV Valve.

      1. PCV valve and or PCV valve line leak or vaccum leak at another location I would replace the PCV valve since they are relatively cheap and check all vaccum lines.

      2. Hi Magnus,

        I have a 2014 Mercedes e300 hybrid the check engine light came on recently showing code p2006 shutter closed in intake bank 1 but also it is showing intake temperature as below

        Out side temperature was 10c

        Air intake temperature bank 1, sensor 1 20.0
        Air intake temperature bank 1, sensor 2 -40.0
        Air intake temperature bank 1, sensor 3 -40.0
        Air intake temperature bank 2, sensor 1 -40.0
        Air intake temperature bank 2, sensor 2 -40.0
        Air intake temperature bank 2, sensor 3 -40.0

        Can air intake temperature affect the closed shutter

        Kind Regards

        Dilly

  2. I have 2001 Lexus RX300, I replaced the fuel pump & the fuel pressure regulator, the car still want start, I hooked up my OB11 SCANNER & found a code ; p0110, my question is can IAT Sensor stop the car from starting?

    1. Author

      @Roosevelt
      If you have access to the scanner, check the value of the intake air temperature sensor while the car is running in the scanner. Intake temperature sensors do not normally make the car to not starting. I would recommend checking the fuel pressure with a gauge to make sure you have ~3 bars on ignition.

      If not, you can check if you get any RPM signal in the scanner. If not, there might be a problem with a crankshaft sensor or camshaft sensor. Also make sure that the immobilizer is OK.

  3. Hi! On my BMW E60 M5 since I have bought it (1,5 years, almost 30k km driven already) I have an issue with slightly rough idle, but only on a warm engine. The issue is more noticeable in case the engine idles a lot e.g. in a traffic jam. Possible to feel then some vibration as well.

    Idle control valves have been replaced, but nothing has changed. Throttle bodies have been cleaned as well. Vacuum leaks have not found.

    No trouble codes identified.

    Some days ago have noticed that MAF sensors show different intake temperatures on bank 1 and 2 i.e. on a hot engine the difference is sometime 5-7 Celsius. Have tried to switch the MAF sensors between banks, but ISTA shows same date i.e. MAF sensors are probably fine. Could it be a MAF wiring issue or such difference might be simply because the air is really warmer in some parts under the hood?

    Unfortunately, did not have a chance to check if MAF sensors should different temperatures on a completely cold engine.

    I understand that in theory different intake temperatures on banks may cause some rough idle due to different fuel mixtures. Could it be true?

    Mass air flow values on idle are almost identical on both banks. About 18-19 kg/s if I remember correctly.

    Any advices where I could dig further? Do not really feel any effect on performance from this slight rough idle issue, but still would like to finally solve it.

    Thanks.

  4. Good day

    i have the some problem with my citroen c3 hdi
    the know the car cant start code is p1113 iat help cant locate the iat sensor in this car.

  5. Hi I have an A3 sportback 2lt from 2011-2012 and now all of a sudden when the exterior temp is really hot (27* +) the the car will either not start or if running just completely shut down. We I try to restart no ways will it start and just making clicking on/off sounds. Yesterday didn’t use the car left in the sun and impossible to start any idea what this could be ??

    Audi recalled the car to check the type of starter we have and told me since its bosch no need to change and problems started just after ???

  6. i have a 2001TS ASTRA 1.8 HATCH .IT WILL BE DRIVE FINE I WILL GO TO DRIVE INTO A DRIVE WAY OR AROUND A ROUND A BOUT WITH THE REVS DOWN AND IT WILL CUT THE ENGINE DEAD WARNING LIGHTS LIGHT UP.IT WONT RE START IMMEDIATLY IF I TURN THE IGNITION OFF FOR 2 MINUTES IT WILL RESTART AS IF THERE IS NOTHING WRONG. WITH OBD2 ON IT ALL GOOD INTAKE TEMP SAY 18 C WHEN IT WARMS UP MINUS 40C. HAVE CHANGED FUEL PUMP .S/PLUGS. MAF.INJECTER CLEANER.CARNT FIND LEAKS….GMS.CAN YOU HELP

  7. Hello !

    Mitsubishi owner, 4N14 engine code, automatic.
    When temperature (outside) goes over 35 degree (C), the engine goes crazy.
    This happened only at load, NOT when the car is stopped and only when rpm is between 1500-1800.
    Big vibrations, rmp up and down (+/- 50 rmp), higher consumtion. If I will increase the rpm (shift in lower gear), the vibrations disapear. At idle, rpm stays still.
    Engine oil was changed regularly also the geabox oil was changed.
    Does anyone have any ideea?

    Thank you !

  8. bI can you show me we’re the air intake temperature sensor is located on the Ford Fiesta 2016 reg 1 .0 litres, I would Appreciate if you could email me and also show me a diagram

  9. Can a bad intake air temperature sensor make a Jeep not start after you drive it and the motor gets hot (not overheating) and you shut the Jeep off it won’t start till the motor pretty much sits over night where it’s completely cooled off and then it will start right back up with no problems

  10. Hi,

    I have a 1997 Ford 460 gasoline engine and it idles around 900. It was around 800 before I set the timing, which it now seems to accelerate better. I have changed the idle control valve, but still idles high. The idle screw does nothing. Throttle body seems free. Could it be the TPS or Air intake TS?

    The timing is set at 30 degrees BTDC with spout connector connected. Is this too much? I have 2 460s and they seem to be peppy at that setting.

    Thanks,

    Ron

  11. I own a Toyota Mark Grand. This vehicle can’t maintain idling upon starting it till I accelerate the Engine…then after it can maintain idling.
    What could be the fault cause.

  12. I have 08 Ford Escape when the outside temp is 70 degrees or more the engine will miss and sometimes dosen’t even have enough power to pull itself, won’t shift into gear right it is an automatic

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