Car Air Temperature Sensor │Air Temperature Sensor (MAT)


Here we will learn about the basic of Air temperature what is their role in the engine and understand the effect of a faulty Air Temperature sensor

Introduction to Air Temperature Sensor or MAT 

Let me begin with a very understandable example we human breathe air (Oxygen), oxygen helps food to break into energy. We use this energy to perform our works in daily life but you have ever wondered what happens if the temperature of breathing air changes around you. Do not worry let me tell you the human body air-breathing system will only work at standard minimum or maximum air temperature. As soon as air temperature goes up or down to a certain level we might feel heavy or exhausted, this feeling nothing but the level of oxygen in the air.
So we all know what condition we are going into maybe it is hot or cold.
But how will the engine be knowing? That air coming inside its body(cylinder) is on correct or standard temperature. So here comes Air Intake Temperature sensor or Manifold Air Temperature (MAT), or charge intake temperature.

What is Air Temperature Sensor or Manifold Air Temperature Sensor (MAT)?

Manifold air temperature sensor measures temperature (hotness & coldness) of air going inside the engine cylinder. Based on air temperature it generates a voltage signal, this signal travels through the wire to ECU(Engine Control Unit or Electronic Control Unit). By processing and compering coming data with standard stored data ECU decides to maintain engine performance & efficiency at an optimum level.
ECU does it by influencing Fuel injection quantity, spark timing, and crank angle.

How does Air Temperature Sensor Work?

Generally, air temperature or manifold air temperature sensor made from doped polycrystalline or semiconductor. These metal oxide change their resistance concerning a change in the surrounding temperature.
So as soon as the temperature of air coming into manifold change so as the resistance of the sensor. If we are using NTC (negative temperature coefficient) increases in temperature result in lowering resistance, which reduces the voltage at the sensor. Opposite will happens with the PTC sensor.

Why we need Air Temperature sensors?

Intake Air Temperature │Manifold Air Temperature Sensor

Air Temperature sensor tells us about incoming air conditions whether it is hot or cold , because if air temperature increases more than 10℃ form engine ambient percentage of  oxygen molecules contained in the air decrees significantly.

 ↑ in temperature will ↓ density of oxygen in the air 

This means if 01 Gram of Fuel needs 40 Gram of air to complete combustion in normal condition now it required more air quantity to complete the same combustion process as molecules of oxygen in air decrease due to increase temperature.

So if an engine does not equip with a MAT sensor it is difficult to maintain exact Air/ Fuel ration to meet the optimum level of performance and efficiency of the engine.

Effect on Engine of a Faulty Air Temperature Sensor

If a Car or vehicle equipped with faulty or having faulty air temperature sensor following could be early symptoms.

            1.Engine Light or diagnostic trouble code on dashboard 
            2.Cold starting problem
            3.Engine power reducing 
            4.Higher fuel consumption 
            5.It also affects the opening of EGR Valve

Reason for Air Temperature Sensor Failure 

 The following are a possible cause of Air Temperature sensor failure. 
            1.Wiring Harness short circuit
            2.Internal or external body crack
            3.Wrong connection
            4.Internal short circuit
            5.Dirty sensor surface 

Troubleshooting of Air Temperature Sensor 

          1.Check electrical wiring & connectors
          2.Read dashboard after connection it diagnostic tool or OBD-II tools
          3.Check battery or input supply to the sensor 
          4.Check for any crack, corrosion

Easy Way to Test & Check MAT or Manifold Air Temperature Sensor

These are step which you can follow to test and check MAT:

Step 01

Every manufacturer defines their air the temperature sensor  internal resistance so when temperature of air change so does its resistance by taking a  reading from the dashboard will able to tell whether sensor working or not.
If reading  changes as per guide or specification of a sensor means  sensor in good condition.
Ex-  At 25℃ --7KΩ and At 800℃ -- 320Ω

Step 02

Start searching for short circuit, damage or crack of wiring harness connector connected with sensor and ECU.
Simply use a standard multimeter connects its one end to one wire other with second wire if continuity is found by connecting multimeter means there is no short circuit or damage in wiring. 
So check of physical damage of connector or pins of sensor & ECU.

Step 03

The Last check for power supply, some time due to oxidation at battery point disturbance  in power supply can be occur due to which low voltage reaching at a sensor or ECU also cause problems.
Also, check for grounding wire.Standard voltage supply of electrical and electronic units in vehicles is 5V, 12V, 24V.

Installation or Removal procedure of Air Temperature Sensor

Follow four simple steps during  installing and removing of MAT

              1. Stop or turnoff ignition key: This for safety purpose before starting the removal and                                installation process
              2Location of sensor: Air temperature sensor mounted near air manifold housing 
              3. Wiring & Connectors: Remove wiring and connector in b/w ECU and sensor very                             carefully because some time due to high heat they might get brittle and pronto damage.
                 After checking it continuity reinstall its in the same way and on same route.
            4.Use Special or standard Tool: Different manufacturer made a unique sensor connector                     which connect body to manifold housing , without using defined tool may damage or cause 
            difficult to remove or install a sensor. Inspect it check for any crack or internal damage and 
             reinstall in the same manner.

Safety Precaution during installation and removal process 

        1.Make sure the vehicle is always grounded during instillation or checking process
        2.Service area should be free from dirt,smog, highly volatile liquid
        3. Should have a fire extinguisher near the service area
        4.Use heat resistance gloves 

Learn about  Different Type of Temperature Sensor

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