Home Diagnosis and TroubleshootingElectrical System and Electronics Car Sensor – How Many Are There On The Car?

Car Sensor – How Many Are There On The Car?

by Jordan Harris
Car Sensor

Have you ever asked the question what is a car sensor? What makes a car sensor and what is its goal? If you are asking these questions then you are at the right place because there will be a lot to cover on this topic where we will learn everything about these sensors.

Having a problem with these components can be really tricky to deal with. Mainly because whenever a sensor fails, you will be greeted with a check engine light and you will be scratching your head about what this light means and why it is there.

Luckily for you, there are tools that will help you out when it comes to sorting out this problem on your vehicle. These tools are basically lifesavers in these situations and will definitely make your life much easier and you will have no trouble diagnosing them. But still, you need to learn the basics of car diagnostics. Still, you shouldn’t worry because we are going to help you out with that.

First, we are going to learn what is a car sensor. Then we will learn how many of these components are on the car and the tools you will need to tackle them. After that, we will learn the complete car sensors list and learn which are the most common sensors, how they work and the symptoms they produce. So, if you want to learn more about this, follow along.

What Is A Car Sensor?

Now before we dive into how many sensors are there, let’s learn more about what is a car sensor in general. Knowing this will be of great benefit for you to understand how this component works on the car and how you can tackle a problem with a specific sensor. So, let’s cover the basics briefly before we dive into more complex topics.

So, what is an automotive sensor? Well, start from the beginning. Back in the good old days, there were no sensors on cars. Everything was analog, even the sensors were analog and they relied on oil pressure, fuel pressure, etc. And there were not many of these units. There were only sensors for the RPM reading, the oil pressure gauge, and simple things such as these.

Nowadays cars are packed with tech and everything is digital. This means that modern sensors are electronic components. These components communicate with the car computer which is known as PCM or ECM (Engine Control Module).

These sensors have a sensing unit that acts as a probe. This probe reacts to some properties such as proximity, pressure, vacuum, temperature, and other properties.

Then this unit produces a certain voltage which is known as a signal. And then the sensor transmits this data to the computer and the computer evaluates the data and determines what to adjust inside of the engine. Pretty straightforward. In the following chapter, we are going to explain the basic diagram for these car sensors.

Sensor Diagram

Now let’s learn more about the car sensor diagram. What is the diagram in the first place? Well, this diagram is basically a map of the electrical circuit of the sensor. Every sensor has a certain map that you can read and learn how to diagnose the right way.

The older sensors are two-wire sensors in most cases. The body of the component serves as a ground and there are two separate wires that go from this component to the computer. One of them is the 5V voltage supply and the other wire is the signal wire that goes to the PCM and informs the PCM about the readings that this sensing unit gets.

More modern cars have three-wire sensors. Three-wire sensors include three pins. One wire is the ground, the second wire is the signal wire and the last wire is the 5v supply for this sensor. Simple as that.

You need to understand that every one of these components has an electrical circuit. And you should differentiate them from solenoids.

Solenoids are also electrical components but they have a different task and that is to open and close. They don’t measure anything. So, a lot of people are confused by this when they learn about the car sensor, so that should clear things up. What is the same is the diagnostic process. They are both diagnosed with the tools that we are going to discuss next.

How Many Sensors Are In A Car

Now let’s learn how many of these sensors are in a car? What is the answer to this question? Well, the answer is not that simple because different cars implement a different amount of sensors.

But the bare minimum of sensors in a car is about 15. But this is only the beginning since many luxury cars include a ton of features and this number can rise up to 30 or more in some cases.

The most important ones for you are the ones that regulate the work of the engine and allow it to perform as it should.

In addition to these sensors, also the sensors that are for the safety systems are really important for you. These systems include the ABS (anti-brake locks), traction control, airbag systems, and other important systems that we are going to cover later on. But first, let’s take a look at the tools you will need in order to tackle these components.

Tools Needed To Diagnose Sensor Issues

So, what are the tools that you will need to diagnose a car sensor? Well, there are two really important tools for you in this case.

The first tool that you will need is the OBD2 scanner. With this scanner, you will be able to get access to the PCM/ECM. Then you can scan it for codes and if one of these sensors is broken, you will get feedback. This feedback will resemble a trouble code.

The codes for most sensors start with “P”. The letter P stands for Powertrain. Which includes the engine transmission and also the wheels.

Then once you got the feedback from the computer and you learned that one of your sensors is showing a code. The next step will require you to get a tool that is known as a multimeter.

Car Sensor

Most sensors are diagnosed by backprobing them. And by backprobing we mean that you will need to put some metal clips into the connector while the sensor is attached and then measure the values that it produces with a multimeter.

Or in some cases when this is not possible, you can bench test these components with a multimeter as well. Also, some OBD2 scanners will give you the ability to access live data and see how these specific sensors work and if the values they produce are as the factory spec should be.

For reference data on how a sensor should behave you can consult online. Just browse the sensor name and reference values. Then you will be able to learn what are the reference values for this car sensor. Now enough on this topic, let’s dive into the different sensors and learn more about them and their symptoms.

Car Sensors List

Now let’s cover the car sensors list. What is worth noting is that we are going to stick to the powertrain sensors. This means that these are all the sensors that are associated with the powertrain.

As you probably know, the powertrain consists of the engine, transmission, and wheels. All, the components that basically help your car move forward. We will also cover the most common sensors that break down. We will list their characteristics as well as the symptoms that they produce. So, let’s get started.

What Is A MAF Sensor On A Car

So, let’s start with the first car sensor this is probably one of the sensors that are notorious for breaking down and causing a ton of headaches to owners. And that is the mass airflow sensor, also known simply as MAF.

This component has a simple task and that is to measure the air that passes through the intake. This is a really important task since the computer needs some data to be able to adjust the air to fuel ratio of the engine.

Without the MAF, the computer will never know how much air is sucked into the engine and the car will produce a ton of symptoms. Namely, rough idle, engine misfires, poor performance, and the engine will like to run either too lean or too rich.

Sometimes this component can clog up and this can make it malfunction. But in most cases, it fails and has to be replaced with a new sensor. And this sensor is rather costly, costing about $250 to change.

What Is A MAP Sensor On A Car

The next car sensor that we are going to cover is the manifold absolute pressure sensor. Which is also known as MAP.

This sensor was used in the past as a standard before the MAF was invented. Then it was largely replaced by the MAF. This component basically does the same thing as the MAF. It evaluates the airflow in the intake manifold based on the overall vacuum pressure that is created.

But this MAP sensor is still used on older cars from the 90s as well as turbocharged diesel and gas engines. There is a MAP and a MAF on all diesel engines. So, if you have a Powerstroke or a Cummins diesel, you probably have a MAP sensor.

Sadly, this component can break down and cause the same symptoms as the MAF. These include a rough engine idle, misfires, and poor engine performance.

What Is An O2 Sensor In A Car

The next car sensor that we are going to cover is the O2 sensor. This one is also known under the name of air to fuel ratio sensor or oxygen sensor.

And what it does is precisely that as its name implies. It helps the engine to adjust the air to fuel ratio in the car.

This component is mounted on the exhaust pipe. In fact, there are two of these sensors. One is located before the catalytic converter and one of them is located after the catalytic converter. The first is known as upstream while the latter is the downstream sensor.

Both of them measure the level of oxygen in the exhaust pipe and deliver this data to the PCM and then the PCM adjusts the air to fuel ratio so your car works well. If this component is broken, you will face a ton of different symptoms.

Namely, the check engine light, engine misfires, rich air to fuel mixture, poor engine performance, black smoke from the exhaust, rotten egg smell, and failure in the emissions tests. This sensor is more important than the MAF. So, you definitely want to have it in proper working order.

What Is A Knock Sensor On A Car

Now let’s cover another car sensor and that is the knock sensor. So, what this component is all about? What does it really do? Does it detect knocking?

Well, yes, this is basically a small microphone that is installed on the engine, this component works at really limited frequencies that allow it to notice if there is knock development inside of the engine.

Engine knock as you know is the situation when there is a knock development from low octane gas or poor engine timing. And what this component does is helps in adjusting the engine timing and air to fuel mixture.

And even though this component is really small. It can affect the work of the engine. Symptoms of this component can include knocking sound coming from the engine, poor engine performance, and overall increased wear and tear inside of the engine. This is why you want to fix this component before it fails completely.

What Is A Cam Sensor In A Car

The next on our list is the camshaft position sensor. This is another really important car sensor that the work of the engine really depends on.

Without this component, the computer will not be able to monitor the position of the camshafts. So, whenever you have a problem like this the engine will work badly. There will be stalling issues, poor acceleration, and poor fuel economy.

In addition to this, whenever this component fails, it will prevent your engine from starting. You will continuously crank the engine before it starts or will not be able to start at all. So, if you don’t want to end up not being able to start the car, replacing this car sensor should be one of your top priorities.

What Is A Crankshaft Position Sensor In A Car

And the next car sensor that we would like to cover is the crankshaft position sensor. This sensor is pretty similar to the one for the camshafts.

The crankshaft as you know is the component that rotates and makes the engine run. As the crankshaft rotates, there should be a component that will monitor its position.

Monitoring the position of the crankshaft is essential because by doing this, the engine will be able to adjust the ignition timing and other important factors.

So, whenever this component fails, you will face the same symptoms as the previous one. The car will run poorly and it will eventually stall, then you should start the engine again and again will stall. Also, another very common symptom is when the car doesn’t want to start on the first try.

Whenever this sensor fails, you will continuously crank the car until eventually starts. And this could be detrimental to the battery of your engine and when this sensor fails completely, you will not be able to start the car at all.

What Is A Coolant Temperature Sensor

The next car sensor that we would like to discuss is the coolant temperature sensor. This is also another really important component that allows the car to run well. Without it, the car will simply struggle. But what this component does in the first place?

Well, this sensor plays a big role in the proper work of the engine. What it does is when the engine starts, this component checks the temperature of the coolant.

And if the temperatures of the coolant are really low, this will be like an alarm for the computer to adjust the air to fuel ratio. The computer will make the car run richer because when you perform cold starts you need that little bit of extra fuel into the system because if you don’t have it, the engine will stall immediately after starting.

This sensor also helps the EGR system as well it also helps with the activation of the radiator fan when temperatures of the coolant get really hot.

And when this component fails, you will face a ton of symptoms. Namely, the check engine light, poor idle, engine running rich if it detects cold condition all the time.

Or if it detects a hot situation you will have extremely lean air to fuel mixture in cold temps and inability to start the car under these conditions. Overall, this car sensor is a nightmare, so you need to replace it, you cannot drive like this.

What Is A Speed Sensor In A Car

Now let’s cover the last car sensor on our list and that is the speed sensor. In fact, there are two types of speed sensors. One that is mounted on each wheel and a Vehicle Speed Sensor that is mounted on the transmission.

The wheel speed sensors are there to monitor the vehicle’s speed as well as to aid the ABS, Traction Control, and other safety systems when it comes to their work. And when they fail they will cause problems with these systems such as the ABS and TC.

And by doing this they can jeopardize your life since you will not have safety systems in proper working order.

While the VSS is a sensor that is mounted on the transmission. And when this component breaks you will have symptoms such as issues with shifting, cruise control not working, and a non-working speedometer.

Oxygen Sensor Facts:

  1. Oxygen sensors are crucial for internal combustion engines to achieve the proper fuel-to-oxygen ratio to maximize engine efficiency and minimize emissions.
  2. Most vehicles manufactured after 1980 have at least one oxygen sensor, but the number of sensors differs depending on the engine type.
  3. Faulty or failing oxygen sensors can cause the Check Engine Light to illuminate and result in a rough engine idle, misfiring engine, worsening fuel economy, or failed emissions inspection.
  4. Even if your car’s engine is not exhibiting any symptoms, it may still be time to replace your existing oxygen sensors, which are designed to wear out over time.
  5. The recommended service interval for replacing oxygen sensors varies depending on the make and model of the vehicle and the type of sensor.
  6. OBD-II scanners can help diagnose potential oxygen sensor problems, but other engine problems may register the same diagnostic code.
  7. A reliable mechanic with a diagnostic scan tool can pinpoint which oxygen sensor has failed and recommend replacement options.
  8. Oxygen sensor replacement cost varies depending on whether you do the job yourself or hire a mechanic, with many sensors costing between $20 and $100 and labor costs typically around $150.
  9. Keeping your vehicle’s oxygen sensors in good working order is critical to achieving optimal engine performance, gas mileage, and passing emissions inspections.
  10. If you suspect a problem with your oxygen sensors, it is important to address it quickly to prevent further engine damage and potential safety hazards.


In this article, we have covered quite a bit when it comes to the car sensor. First, we learned the basics when it comes to sensors and learned what these components do and the basic diagram. We also covered how many there are on a car.

After that, we discussed the most common sensors that break down on a car. How they work and also the symptoms they produce when they break down.


Now let’s answer some frequently asked questions.

Will Bad O2 Sensor Cause Car To Shut Off

No, it will not cause the car to shut off, at least not in 99% of the situations. Whenever this sensor fails, the car starts to run really rich and there will be poor engine work that’s for sure. But it will still work though. So, you don’t have to worry about your car stalling from a bad O2 sensor.

What Does A Car Do When The Oxygen Sensor Is Bad

When this sensor fails, the car will start to run really rich and this will cause symptoms. Namely, the check engine light, poor fuel economy, black smoke from the exhaust, rotten egg smell, high emissions, and overall poor engine work. The engine will jerk, hesitate, and will have power surges.

How Much Is A Sensor For A Car

On average, a new sensor costs between $150 and $350. It really depends on what type of sensor we are talking about. Some of them are fairly affordable. The MAF and the O2 sensors are usually the most expensive ones to replace.

Can A Bad Coolant Temperature Sensor Cause Car Not To Start

Yes, it could cause the car not to be able to start. So, why is this the case? This is the case because this sensor monitors the coolant temperature. And if it senses bad reading, it will not allow more fuel to enter into the combustion on a cold start. Thus, the car not being able to start in the process. Or immediately stalling after start can occur.

Can I Drive My Car With A Bad MAP Sensor

Yes, you can drive a car like this. But this component is crucial when it comes to the adjustment of the air to fuel ratio. So, when it doesn’t perform well, it will lead to problems like lean air to fuel mixture, misfires, check engine light, and poor performance.

Where Is The Outside Temperature Sensor On A Car

This component is usually mounted behind the front grille or behind the bumper on the crash bar or somewhere close to it. The exact location can depend on the car, so you better look for your exact make and model location.

You may also like

Leave a Comment