There are a lot of sensors used in modern-day automobiles that help in the proper functioning of the vehicle, reducing emissions, increasing efficiency as well as improve the safety of the vehicle. Every sensor has a specific function and location assigned to it. The data from all the sensors is sent to the Engine Control Unit (ECU) which then interprets it and takes action accordingly such that the vehicle functions in an optimal manner.
So, today at The Mechanical post we’ll take a look at the Different types of sensors commonly found in automobiles along with each of their functions and location.
You can get your Free copy of the PDF on the Different types of sensors used in automobiles at the end of the article.
Following is the list of different types of sensors used in automobiles:
- Mass Air Flow Sensor (MAF)
- Throttle position sensor
- Crankshaft position sensor
- Camshaft position sensor
- Manifold Absolute Pressure sensor (MAP)
- Knock sensor
- Fuel Temperature sensor
- Coolant Temperature sensor (CTS)
- Exhaust temperature sensor
- Oxygen sensor
- Vehicle speed sensor
Mass Air flow Sensor (MAF)
To determine the Mass flow rate of the air entering the I.C engine such that proper air-fuel ratio can be maintained.
For what purpose is the Mass Air flow Sensor used?
The mass airflow sensor also commonly known as the MAF sensor is a type of sensor used in cars to calculate the amount of air that enters the I.C engine during the intake stroke.
The MAF sensor along with data from other sensors helps the ECU to determine how much fuel must be added by taking into account the amount of air available. This results in optimized operating conditions as well as helps in reducing pollution.
Throttle position sensor
The function of the throttle position sensor is to sense the position of the throttle plate that helps the ECU in deciding how much fuel must be added.
What is a Throttle position sensor?
When the driver presses the accelerator pedal it opens the throttle plate accordingly. So in order for the ECU to understand how much the driver has pressed the pedal, a throttle position sensor is used.
The sensor does not measure the position of the pedal being pressed by the driver. Rather it measures the position of the throttle plate at the beginning of the intake manifold which is operated by the pedal.
The throttle position sensor helps the ECU to control the amount of fuel in proportion to the air entering the cylinder and thereby varying the speed of the engine.
Crankshaft position sensor
The function of the Crankshaft position sensor is to measure the position of the crankshaft that helps the ECU to understand the engine speed, the position of the piston inside the cylinder, and much more.
The Crankshaft position sensor is mounted to the engine block such that it faces the timing rotor which is mounted on the crankshaft.
What is a Crankshaft position sensor and why is it used?
The crankshaft position sensor plays a crucial role and helps the Engine Control Unit (ECU) understand data that is very important for the proper functioning of the engine.
With the help of the Crankshaft position sensor, the ECU can get to know at what position is the piston inside the cylinder is at a given instant. The information provided by the crankshaft position sensor also helps the ECU in controlling the injection of the fuel and the ignition system timing.
Camshaft position sensor
The function of the Camshaft position sensor is to measure the position of the camshaft at a given instant. This helps the ECU to better understand and adjust the fuel injection as well as ignition system timing.
The Camshaft position sensor is located near the cylinder head such that it is close to the camshaft.
What is a Camshaft position sensor?
The camshaft position sensor and the crankshaft position sensor both work together in order to give the ECU a complete picture of what processes are going on in the engine at the particular moment.
The Camshaft position sensor can be used by the ECU to perform actions like cylinder selective knock control or sequential fuel injection.
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Manifold Absolute Pressure sensor (MAP)
The function of the Manifold absolute pressure sensor is to sense the pressure of the intake air and then accordingly decide the air-fuel proportions to be sent to the engine.
What is an Manifold absolute pressure sensor?
The Manifold Absolute Pressure sensor or the MAP sensor is a device situated in the intake manifold and is used to calculate the pressure of air going to the engine. The higher the pressure, the higher will be the mass of air and hence more fuel can be used.
This sensor helps the ECU in determining the amount of air and fuel that has to be sent to the engine.
The function of the Knock sensor is to pick up the vibrations and sound coming from the engine and convert them into electrical signals.
The Knock sensor is attached directly to the outside of the engine block. However, in some instances, one can find the sensor beneath the intake manifold.
What is a Knock sensor and how does it work?
The knock sensor is used to sense the sharp sounds and vibrations coming from the engine due to premature combustion. This type of premature combustion is known as knocking in an I.C engine. In knocking the combustion starts even before the spark plug ignites the mixture which is bad for the engine.
Thus to prevent knocking a knock sensor is used, which detects knocking in the engine and then converts it into electrical signals which are then sent to the Engine Control Unit (ECU). The ECU then processes the data and then decides whether to change the ignition timing or not.
Fuel temperature sensor
The function of the Fuel Temperature sensor is to sense the temperature of the fuel and on that basis, the amount of fuel to be sent to the engine is decided.
The Fuel Temperature sensor is located in the fuel tank and is often part of the fuel pump assembly.
What is a Fuel temperature sensor?
The fuel density changes with a change in temperature. The higher the temperature, the lower will be the density and vice versa. A hot fuel means lower density and therefore more amount of fuel must be injected into the cylinder.
Thus, it is necessary to monitor the fuel temperature and compensate for the change in fuel density. The fuel temperature sensor helps the ECU to improve the injection accuracy as well as meet emission standards.
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Coolant Temperature sensor (CTS)
The function of the Coolant temperature sensor is to tell the ECU that how warm the engine is running by measuring the coolant temperature.
The Coolant Temperature sensor is usually located near the thermostat valve in the coolant passage.
What is a Coolant temperature sensor and why is it important?
The coolant temperature sensor helps the ECU understand whether the engine is running hotter or colder. Then accordingly the steps are taken by the ECU to maintain the temperature of the engine at an optimum temperature. This is important as a cold engine requires a different amount of fuel as compared to a hot engine.
Exhaust gas temperature (EGT) sensor
The function of the Exhaust gas temperature is to measure the temperature of the hot exhaust gases that helps the ECU in regulating the air-fuel ratio.
What is an EGT sensor and why is it used?
Just as the name suggests, the EGT or the Exhaust Gas Temperature sensor is used to determine the temperature of the exhaust gas.
The EGT sensor is useful for the ECU to confirm that the proper air-fuel mixture is being sent to the engine. Changes in the air-fuel ratio can result in a change in the exhaust gas temperature hence it needs to be monitored by the EGT sensor.
The Oxygen sensor is located between the engine and the catalytic converter in the exhaust manifold.
What is an Oxygen sensor?
The Oxygen sensor is used to measure the amount of oxygen that comes out of the engine and then reports it to the ECU (Engine control unit). If the sensor senses more amount of oxygen it means that the mixture is rich whereas if less oxygen is detected then it would mean that the mixture is lean.
So on the basis of the data obtained from the Oxygen sensor, the ECU decides the amount of fuel entering the cylinder and thereby compensates for the excess fuel or excess of air.
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Vehicle speed sensor (VSS)
As the name suggests, the vehicle speed sensor is used to measure the speed of the transmission output shaft or the vehicle wheel and send it to the ECU.
What is a Vehicle speed sensor (VSS) and what does it do?
The vehicle speed sensor helps the Engine control unit in a number of ways by telling the real-time speed of the vehicle. The data provided by the VSS is also used by driver assistance systems such as ABS, TCS, ESP or ACC, motor control units to determine the wheel speed.
So, that’s a brief on the different types of sensors found in cars. There are many more sensors used in an automobile, however, we have covered the most common and basic ones.
Can you name some other sensors that you know of? Let us know in the comments, we are willing to hear from you.
Till then Keep Learning!