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A Guide on Everything You Need to Know About Sensors in Cars

A Guide on Everything You Need to Know About Sensors in Cars

Today’s modern vehicles are equipped with a variety of sensors. Thanks to these sensors in cars, on board computers can make decisions based on what is happening in and outside of the vehicle since they monitor almost everything. They perform different tasks, such as identify and prevent potential issues before they cause problems. These sensors have been developed to make sure that your vehicle is operating smoothly, efficiently and safely.


 

As you read, you will learn how many sensors a car usually has, what they do, where they are located, and how to make sure they are working properly. 

How many sensors are there in a car?

According to a report, the market demand for automotive sensors could be worth more than $26 Billion and is still increasing as of this writing. 

 

Sensors are being installed throughout the vehicle to meet advancing security and efficiency standards as well as address new environmental standards and requirements.

 

According to experts, the number of sensors used in vehicles will increase as the electronic systems increase. Up to this time, each vehicle has around 60 to 100 sensors on board and we can safely assume that these figures will increase as cars get smarter.

 

As a matter of fact, a recent report says the number of sensors is expected to reach as many as 200 per vehicle in line with current trends.

How does a sensor work in a car?

They are the sensory organs of a car. A core component of electronic control systems, they are designed to record physical or chemical variables and convert them into electrical signals. Like what we have mentioned earlier, with the help of these sensors, onboard computers make decisions based on the electrical signals or the data collected.

What sensors are used in cars?

With the advancements in technology, sensors enable modern vehicles to become more safer and cleaner than ever. They provide the key information for effective and clean fuel combustion in the engine. Therefore, they make exhaust emissions values and fuel consumption reduced significantly. Lastly, sensors in cars support the reliable functioning of high-efficiency exhaust re-treatment systems, such as the diesel particulate filter, controlled 3-way catalytic converter, or the DeNOx catalytic converter.

 

Types of Sensors

Over the years, the number of different types of sensors used in cars have increased significantly. A lot of new types of sensors have been seen particularly in the area of convenience and safety electronics. 

 

Fundamentally, sensors can be classified as follows: 

  • Position sensors (angle/distance sensors) 
  • Acceleration sensors
  • Speed and velocity sensors
  • Temperature sensors
  • Pressure sensors
  • Torque and force sensors
  • Gas sensors
  • Flowmeters

 

  • Sensors from Car Body Electronics
    • Wheel speed
    • Brake lining wear
    • Speed, transmission
    • Coolant level/Engine oil level
    • Speed, distances travelled

 

  • Sensors for Engine Control
    • Pulse sensor, crankshaft
    • Camshaft position
    • Air mass meter
    • Intake air temperature/Outside temperature/Interior temperature
    • Coolant temperature
    • Throttle position
    • Knock sensors
    • Intake pipe pressure
    • Oxygen sensors

 

  • Air Bag and Crash Sensors

 

Position sensors (angle/distance sensors)

They are used to capture the position of the following:

  • The steering angle
  • Fill level in the fuel tank
  • Throttle valve
  • The accelerator of brake pedal
  • The angular positions and distance in diesel injection pumps
  • The angle of tilt and so on.

The radar and ultrasonic sensors used to calculate distances from obstacles for modern driver assist systems also can also be included in this category.

 

Acceleration sensors

These sensors record the acceleration of the vehicle body and are used in passive safety systems and driving stability systems.

 

Passive safety systems include: 

  • Seat Belt tensioners
  • Roll bars
  • Airbags

Driving stability systems include: 

  • Anti-lock Brakes
  • Electronic stability control or ESC also known as electronic stability program or ESP

 

Velocity and Speed sensors

These sensors are used to calculate the following:

  • The speed of camshafts
  • Crankshafts
  • Wheels
  • Diesel injection pumps

Yaw-rate sensors also belong in this class or category. A Yaw-rate sensor is a device that works like a gyroscope which measures a car’s ywa-rate, its vertical axis and angular velocity. The angle between the car’s velocity and heading is called its slip angle, which is in line with the yaw-rate.

 

Temperature sensors

These particular sensors are the ones responsible for capturing temperature readings. They measure the following: 

  • Interior and ambient temperatures
  • Coolant temperature
  • Suction or charge air temperature
  • Engine oil temperature
  • Evaporator temperature or air conditioning system
  • Tire air temperature, etc.

 

Pressure sensors

This type of sensor is used to monitor different kinds of pressures, such as: 

  • Fuel pressure
  • Brake pressure
  • Tire pressure
  •  Charging or suction pressure
  • Modulation pressure for automatic transmission
  • Hydraulic reservoir pressure for power steering or anti-lock braking system (ABS)
  • Refrigerant pressure for air conditioning system

 

Torque and Force sensors

This type of sensor is utilized to measure forces, such as: 

  • Drive
  • Pedal force
  • The vehicle occupants’ weightfor adaptive restraint systems
  • Steering torque and brake forces

 

Gas sensors

Sensors like this read the composition of the exhaust gas or detect dangerous substances in the fresh air supply. There are two types of this sensor, which include:

  • Oxygen sensor
  • Nitric oxide (NOx) sensor

 

Flowmeters

Flowmeters are utilized to capture the fuel requirement and the amount of air sucked in by the engine.

 

Sensors from car body electronics

 

Wheel speed

It is utilized by GPS systems to compute the distance travelled as well as by driving safety systems such as ASR and ABS as a speed value. 

 

Brake lining wear

The brake wear sensor is typically situated on the brake linings and is subject to the same wear. A wear indicator tells the driver that the brake lining has worn out and the wear limit has been reached.

 

Speed, transmission

The transmission sensor picks up the transmission speed. The control unit uses the speed signal for precision control of the shift pressure during shifting and to determine which gear should be engaged when.

 

Coolant level/Engine oil level

For increased comfort and operational safety, levels such as coolant, washer fluid, and engine oil are observed with level sensors. These sensors send a signal to the engine unit which then activates an indicator light.

 

Speed, distance travelled

The distance sensor is utilized to pick up driving speed. It is usually mounted on the rear axle or transmission. The information obtained is needed for the cruise control, converter slip control and speedometer.

 

Sensors for Engine Control

 

Pulse sensor, crankshaft

The sensor that picks up the position of the crankshaft and the engine speed is called the crankshaft sensor. To calculate the ignition and the injection pulse, the control unit uses the values which the crankshaft captures.

 

Camshaft position

The camshaft sensor is situated at the cylinder head. It scans a ring gear at the camshaft. The information is then used, for example: 

  • For the start of injection
  • For the signal to activate the solenoid valve
  • For the nozzle/pump injection system
  • For cylinder-specific knock control

 

Air mass meter

The meter is placed between the intake manifold and the air filter housing. It measures the air mass sucked in by the engine. This variable gives the basis for computing the fuel quantity that is required by the engine.

 

Intake air temperature/Outside temperature/Interior temperature

The temperature of the ambient air is captured by the air temperature sensor. The values measured are used as correction values for the injection system or to control various systems, for example, the air conditioning system. Depending on the air temperature that is to be measured, the installation location will differ. For example, the sensor for the intake temperature is situated in the air duct for the intake air.

Coolant temperature sensor

This sensor is screw-mounted within the cooling system. It records the temperature through the gauge tip that protrudes into the coolant. To adapt the amount of fuel injected to the engine, the control unit uses this value.

 

Throttle valve sensors

These sensors are fastened to the throttle valve axle. They keep track of the opening angle of the throttle valve. Based on the values, the engine electronics computes the fuel quantity which is injected based on other determinants.

 

Knock sensors

An uncontrolled form of combustion in a gasoline engine is called knocking. It must be checked and regulated since continuous knocking can damage the engine. Based on the knock sensors’ voltage signals, the engine control unit regulates the ignition point in a range just below the knock limit. Knock sensors are always being monitored by the control unit.

 

Intake pipe pressure

Intake pipe pressure sensors measure the intake pipe vacuum downstream of the valve and send this information to the engine control unit in a form of electrical signal. This value, along with the value of the air temperature sensor is combined so that the air mass sucked in can be calculated.

 

Oxygen sensors

In order to ensure an optimum combustion mixture at all times, the oxygen sensor measures the unburnt oxygen content in the exhaust gas. 

 

Airbag crash sensors

The widely used type of sensor is the electromechanical designa gas dampened ball and tube design. Held in place by a small magnet, the sensor is simply a small tube with a switch at one end and a gold plated steel ball at the other. Once the sensor receives a potent jolt enough to knock the ball loose from the magnet, the ball will roll down the tube, hit the switch and close the circuit. The tube is slanted upward so the ball can return to its original position after an impact. 

 

Panic or severe braking alone cannot cause an airbag to deploythey only deploy in crashes. Frontal airbags are typically designed to deploy on moderate to severe frontal or near-frontal crashes, which are described as crashes that are comparable to hitting a fixed, solid barrier at 8 to 14 mph or higherequivalent to hitting a parked vehicle of similar size at about 16 to 28 mph or higher.

How do I know if my airbag sensor is bad?

Airbags are one of the most vital safety features of a vehicle and one should always ensure that they are in good working condition. 

 

Once the driver puts in the key and starts the vehicle, the airbag control module evaluates the airbag sensor circuit and determines if it is working properly. The airbag warning light will illuminate on the dashboard whenever the vehicle gets started to indicate that the sensor is working fine. Nevertheless, if the light remains on after the car has started, it means there is a problem.

 

Here are the most common ways to determine airbag problems:

 

 

  • Airbag light

 

The most common and visible symptom is that the airbag light is lit up or flashing on the dashboard. This means that the airbag function is disabled.

 

 

  • Check it with a Diagnostic tool

 

The best and most accurate way of checking the airbag sensors is through a diagnostic scan tool. According to experts, it is a wise move to take your vehicle to a trusted technician or car repair facility to find out exactly what is causing the problem. 

 

Note: 

Multimeters should not be used while testing the airbags as it can trigger the deployment of airbags.

 

 

  • Airbag Battery backup drained

 

If your car’s battery was recently depleted, there’s a huge possibility that the airbag battery backup was drained as well, which could cause the light to flash in the dashboard. This problem will easily go away after fully charging the vehicle’s battery again. Nonetheless, you would still have to remove the soft-code error with the diagnostic tool.

 

 

  • Faulty Airbag Clock Springs

 

By continually interweaving in and out against the steering wheel, the airbag clock maintains the consistency between the airbag and the electrical wiring. The circuit bands wear out over time and can cause the airbag system to register a code error, which will cause the airbag light to flash in the dashboard. The clock spring issue is burdensome to diagnose at home, so there’s a probability that you will end up wasting your time doing it by yourself. In this case, you will have to take your vehicle to an auto mechanic who will use a diagnostic tool to determine the cause of the problem.

 

Conclusion

Sensors in cars may be small in size but they have important functionsto ensure safety and comfort.