Different Types of Sensors in a Car and its Functions (2024 Updated)

Published on 30 Nov, 2021, 12:50 PM IST
Updated on 27 Jun, 2024, 9:08 AM IST

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Cars have become more complex over the years with the rise of electronic components, and one of the most critical electronic devices is the sensor. There are several sensors in a car which monitor different aspects of a vehicle and send information to the driver or ECU (Electronic Control Unit). In this article, we throw light on different types of sensors in a car and their functions.

Different types of sensors in a car and its functions

What is a car sensor?

A car sensor is an electronic device that monitors various aspects of the vehicle and sends information to the driver or ECU (Electronic Control Unit). In certain situations, the ECU automatically makes adjustments to the particular component based on the information received from the sensor. The below points cover more details about car sensors.

  • Sensors can monitor various aspects of a car, such as its temperature, coolant system, engine, oil pressure, emission levels, vehicle speed, etc.

  • The human sense organs (eyes, nose, mouth, tongue and hands) are the best examples to understand the working principle of sensors. They send signals to the brain, which then makes a decision.

  • Similarly, car sensors send signals to the ECU to make appropriate adjustments or warn the driver.

  • The sensors are constantly monitoring the various aspects of the car from the moment the engine is fired up.

  • In a modern car, the sensors are everywhere, from the engine to the least essential electrical component of the vehicle.

Functions of automotive car sensor

Automotive car sensors are essential components of modern cars as they provide crucial information to the vehicle's control systems. These sensors measure and monitor various aspects of the car's performance, including speed, temperature, pressure, and other critical parameters.

One of the primary functions of sensors is to improve safety. For instance, the anti-lock braking system (ABS) uses wheel sensors to monitor the speed of each wheel. If a wheel stops rotating while the car is still moving, the ABS will reduce brake pressure to prevent skidding and ensure the driver maintains control of the car. Similarly, the airbag system uses sensors to detect sudden changes in the car's speed, deploying the airbag to protect the occupants in case of a collision.

Another essential function of sensors is to improve fuel efficiency. Sensors like the oxygen sensor, fuel pressure sensor, and mass air-flow sensor work together to optimise the car's fuel delivery system, ensuring that the engine runs efficiently. By monitoring the fuel-air mixture, the sensors can adjust the fuel flow to maximise combustion efficiency, thus reducing fuel consumption and emissions. Sensors play a crucial role in enhancing the car's performance, safety, and efficiency.

25 Types of car sensors

The below table denotes different types of sensors in a car and their functions.

Sensor Function
Air-flow sensor It measures the density and volume of the air entering the combustion chamber.
Engine knock sensor It monitors engine knocking and ensures the air-fuel mixture is ignited correctly.
Engine speed sensor It monitors the spinning speed and position of the crankshaft.
Camshaft position sensor It monitors the position and proper timing of the camshaft.
Manifold Absolute Pressure (MAP) sensor Monitors engine load by measuring the difference between the manifold and outside pressure.
Throttle position sensor Monitor the position of the throttle valve.
Voltage sensor It manages the idling speed of the vehicle.
Oxygen sensor It helps to measure the oxygen level present in the exhaust gases.
NOx sensor It measures the Oxides of Nitrogen (NOx) present in the exhaust gases.
Temperature sensor It monitors the engine temperature.
Fuel temperature sensor It monitors the temperature of the fuel entering the engine.
Speed sensor It measures the speed of the wheels.
Parking sensor It recognises any obstacle present in the front or rear of the vehicle.
Rain sensor It detects rain and sends a signal to ECU to activate the wipers.
Tyre Pressure Sensor Wireless tyre pressure monitoring sensors are mounted inside each tyre on the wheel rim or valve stem.
Yaw Rate Sensor This vital sensor measures the angular velocity of sway or rotation around the car's vertical axis
Steering Angle Sensor This sensor tracks the steering wheel's precise angle and rate of turn using magnetic
Accelerometer This key inertial sensor measures longitudinal and lateral G-forces using a microscopic vibrating element.
Gyroscope This six-axis motion sensing provides vital feedback for stability control, lane change assistance and more.
Blind Spot Sensor This alerts the driver to traffic hidden from view to prevent dangerous lane changes
Night Vision Sensor This sensor uses an infrared camera and displays to enhance the driver's view
Driver Monitoring Camera This camera uses machine vision algorithms to track head position, eyelid closure and more.
Parking Assistance Ultrasound Sensor The parking assistance system warns the driver using audio tones and visual displays
Remote Keyless Entry Sensor This sensor detects encoded radio signals from the remote key fob in close proximity to the vehicle.
Backup Camera Provides a view directly behind the car to the dashboard display screen

  Below are more details of the car sensors that are mentioned in the above table.

1. Air-flow Sensor

The air-flow sensor is typically a hot wire mass air-flow sensor located in the air intake tract. It measures the amount of air entering the engine using a heated wire element that has air flowing past it. The rate of heat loss corresponds to air density and flow. This data is sent to the ECU to calculate fuel injection and spark timing for optimal combustion precisely. Failure causes the engine to run rich or lean resulting in power loss, misfires, stalling or increased emissions.

2. Engine Knock Sensor

The knock sensor is an accelerometer attached to the engine block that listens for vibrations caused by early ignitions or engine knock. Knocking can damage pistons, rings, bearings and liners over time. The knock sensor detects this pinging or knocking sound and signals the ECU to retard ignition timing to prevent destructive detonation. This protects engine components from damage.

3. Engine Speed Sensor

The speed sensor is typically a Hall effect sensor mounted on the crankshaft that monitors crankshaft speed and position as it rotates. This allows the ECU to precisely time the fuel injection and ignition to each cylinder based on the crank location. Proper timing of these events is crucial for smooth engine operation, power delivery and emissions control.

4. Camshaft Position Sensor

The camshaft position sensor is mounted on the cylinder head and monitors the rotation of the camshaft, which operates the valves. This helps the ECU synchronise the opening/closing of the intake and exhaust valves with the fuel injection and ignition events. This precise timing optimises engine breathing for power and economy.

5. MAP Sensor

The MAP or manifold absolute pressure sensor is mounted on the intake manifold. It measures variations in the vacuum pressure inside the manifold as engine load changes. The ECU uses MAP data to calculate load and optimise the air-fuel ratio. Failure causes poor driveability, power loss and emissions issues.

6. Throttle Position Sensor

Mounted on the throttle body, this sensor measures the angle of the throttle valve as the accelerator pedal is pressed. This input helps the ECU determine the driver’s power demand and calculate the required air/fuel ratio and timing. Faulty readings will cause erratic engine behaviour.

7. Voltage Sensor

By monitoring system voltage, this sensor assists in regulating the alternator to maintain proper charge. It also optimises idle speed based on electrical load. The sensor prevents battery drain and overcharging.

8. Oxygen Sensor

Mounted in the exhaust manifold, the O2 sensor monitors oxygen content to determine if the air/fuel mixture is rich or lean. Feedback from the O2 sensor allows the ECU to control the mixture for peak efficiency precisely. Contaminated sensors cause poor economy and emissions.

9. NOx Sensor

Located after the catalytic converter, this sensor detects oxides of nitrogen emissions levels. The ECU uses this data to ensure proper catalytic converter operation and make adjustments to lower NOx emissions. Unburnt NOx indicates engine issues.

10. Temperature Sensor

Coolant, air intake and exhaust temperature sensors measure operating temperatures. The ECU uses these readings to manage ignition timing, fuel delivery, cooling fans, and governing and warning lights to prevent overheating damage.

11. Fuel Temperature Sensor

This sensor uses a thermistor or thermocouple to accurately measure the temperature of the fuel in the supply rail leading to the injectors. It monitors how fuel temperature changes during engine warm-up and hot restarts. Since fuel density decreases as temperature increases, the ECU uses this data to adjust the injector pulse width to deliver the correct fuel quantity. Colder, denser fuel requires less pulse time. The ECU can also modify idle speed based on fuel volatility and vapour pressure at different temperatures to prevent stalling.

12. Wheel Speed Sensor

Magnetic wheel speed sensors use coil wire and magnets to generate an AC signal as the wheel spins. Ring-type active sensors have a toothed ring on the axle that spins past the sensor tip. The frequency and voltage of the signal precisely indicate wheel rotational speed and direction. These active sensors feed data to the ABS, traction control, and stability control systems to detect tyre slip and wheel lock-up under hard braking or acceleration. 

13. Parking Sensor

Short-range ultrasonic sensors located in the front and rear bumpers emit high-frequency sound waves and measure the echo return time to detect close-by obstacles. Advanced digital signal processing determines distance while driving at low speeds or when parking based on the elapsed time between emission and return. The parking assist system warns the driver with audible beeps and visual graphics on the dash display showing obstacle proximity to prevent bumps, scrapes and costlier collisions.

14. Rain Sensor

Optical rain sensors use an LED light source aimed at a prism that reflects light onto a photo sensor at a 45-degree angle. When raindrops hit the glass, they scatter the light, lowering the voltage measured by the sensor. Infrared sensors work similarly but detect the infrared spectrum. The varying voltage caused by raindrops triggers the wiper motor without driver input. This provides added safety and convenience by automatically actuating the wipers when needed.

15. Tyre Pressure Sensor

Wireless tyre pressure monitoring sensors are mounted inside each tyre on the wheel rim or valve stem. They contain pressure transducers, a battery power source, and a wireless transmitter. Dynamic sensors also detect temperature. The sensors broadcast RF signals with pressure and temperature data to a central receiver module. If pressure drops 25% below the driver's set limit, the receiver triggers a warning light to alert the driver to low pressure or a leak before safety is impacted.

16. Yaw Rate Sensor

This vital sensor measures the angular velocity of sway or rotation around the car's vertical axis, known as yaw rate. It uses MEMS gyroscopic sensing elements that vibrate when rotated to detect sideways G-forces. The yaw rate signal assists the electronic stability control module in applying brakes to individual wheels and managing engine throttle to counteract oversteer or understeer slideouts. It helps prevent dangerous spinouts, rollovers, and loss of control, especially in low traction conditions.

17. Steering Angle Sensor

Mounted on the steering column, this sensor tracks the steering wheel's precise angle and rate of turn using magnetic, optical, or potentiometer-based sensing. By detecting handwheel position and movement, it can determine the driver's intent and inputs. This data helps augment stability control, lane departure warning, automatic parking systems and other advanced chassis control functions for improved safety and drivability.

18. Accelerometer

This key inertial sensor measures longitudinal and lateral G-forces using a microscopic vibrating element. Combining these acceleration signals with a gyroscope provides complete 3-axis motion sensing. The data assists airbag systems in determining hazardous impacts and deploying at the right speed and force. It also detects aggressive manoeuvres, hard launches, and extreme body lean for rollover detection and prevention systems.

19. Gyroscope

Microscopic MEMS gyroscopes use vibrating elements to accurately measure orientation and angular velocity around the X, Y, and Z axes. This determines pitch, yaw, and roll rates. Gyro data complements accelerometer inputs to define the vehicle's movement in all directions fully. This comprehensive six-axis motion sensing provides vital feedback for stability control, lane change assistance, and autonomous driving systems to improve safety.

20. Blind Spot Sensor

Radar, ultrasonic, or optical sensors mounted in the rear bumper constantly monitor the vehicle's side blind zones. When other vehicles are detected, LED warning lights illuminate the side mirrors or head unit display. This alerts the driver to traffic hidden from view to prevent dangerous lane changes and collisions. Radar sensors work in all weather conditions, unlike cameras and ultrasound.

21. Night Vision Sensor

This sensor uses an infrared camera and displays to enhance the driver's view well beyond the headlight range. The IR sensors detect heat signatures of living objects based on temperature contrast against cooler backgrounds. Software spots pedestrians, animals, and obstacles on the roadway and provides alerts if a collision appears likely, giving the driver extra reaction time to prevent accidents, especially at high speeds.

22. Driver Monitoring Camera

Mounted on the steering column, this camera uses machine vision algorithms to track head position, eyelid closure, gaze vectors and facial micro-expressions. By monitoring the driver, it can determine drowsiness, distraction and inattentiveness that may lead to accidents. The camera provides audible and dash alerts to wake drowsy drivers or prompt distracted drivers to refocus their attention on the road.

23. Parking Assistance Ultrasound Sensor

Short-range ultrasonic parking sensors are located in the front and rear bumpers. They transmit high-frequency sound waves and measure the echo return time to detect close-range static and moving obstacles around the vehicle during low-speed manoeuvring. The parking assistance system warns the driver using audio tones and visual displays showing object proximity and position to prevent minor scrapes and collisions.

24. Remote Keyless Entry Sensor

This sensor mounted by the driver's door detects encoded radio signals from the remote key fob in close proximity to the vehicle. It confirms the correct key code before unlocking the doors and enabling the push button to start. Without pressing any buttons, owners can unlock, enter and start their vehicle while the key stays in their pocket or purse for convenience.

25. Backup Camera

A wide-angle camera mounted on the rear centre of the vehicle provides a view directly behind the car to the dashboard display screen. This allows the driver to easily identify people, objects and obstacles when backing up that might not be visible through the rear window. The backup camera prevents costly collisions into buildings, poles, and, most importantly - small children and pets in the driveway.

Advantages and disadvantages of car sensors

Below are the advantages of car sensors:

  • Car sensors make driving an easy task.

  • The sensors can easily detect faulty components in a vehicle.

  • Sensors ensure that the engine is maintained correctly.

  • Sensors also enable automatic control of specific functions such as windscreen wipers, headlights, etc.

  • The ECU can make precise adjustments with the information received from sensors.

  • Sensors can also relay warning information to the driver if there is any fault/malfunction with the car’s components.

Here are some of the disadvantages of car sensors:

  • One major disadvantage of having so many sensors on board is that they can fail over time.

  • A faulty sensor can lead to damage to vital components of the vehicle. Getting them repaired or replaced can be an expensive affair.

Car sensors play a crucial role in ensuring that a vehicle operates safely and efficiently. There are many different types of sensors in a car, each with its specific function, but all work together to monitor and adjust various systems and components. It is essential to keep these sensors in good working order to ensure that your vehicle runs smoothly and to prevent potential issues that can arise from faulty sensors.

Frequently asked questions

Here are some of the most common queries and their answers related to car sensors.

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How many sensors does a car have?

The car engine alone has around 15 to 30 sensors that track all functions of the engine. In total, a car can have over 70 sensors that monitor various aspects of the vehicle.

Do all types of cars have sensors?

Yes, all types of cars have sensors. From a small hatchback to a large SUV (Sports Utility Vehicle), all vehicles come equipped with sensors for the efficient functioning of the engine and other components.

What happens if the oxygen sensor is not working correctly?

If the oxygen sensor is at fault, the ECU will not get the information regarding the air-fuel mixture ratio that is supplied to the engine. It can also cause idling problems, jerkiness or issues with power delivery.

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