Almost all modern car engines use a variety of different vehicle sensors to collect the right information and calculate a perfect air-fuel mixture for the best fuel consumption in all situations.
The disadvantage of using many different vehicle sensors is that they can fail within a certain period of time, which can sometimes lead to costly replacements.
But which sensors are installed in your vehicle and what function do they have? In this article, you will learn about all kinds of common car sensors that you can find in your car engine.
More information and pictures of all car sensors can be found further down in this article. The shape, price, and arrangement may vary depending on the car model, this is general information for common cars.
Car Sensors Used in a car engine list
|Coolant temperature sensor||Measures the temperature of the coolant||Coolant hose/Cylinder Head|
|Intake Air Temperature sensor||Measures the Air temperature flowing to the engine||Inside the MAF sensor or after the air filter box|
|Mass Air Flow Sensor||Measures the Air Mass going into the engine||Hose between air filter box and throttle body|
|Manifold absolute pressure sensor||Measures the pressure in the intake manifold||At the Manifold|
|O2 Sensors (Lambda)||Measure the Oxygen in the exhaust gases||At the exhaust pipe|
|Knock Sensors||Monitor detonations from the engine||On the engine block|
|Crankshaft Sensor||Measures the position of the crankshaft||Low fitted on the engine. Often in the engine block|
|Camshaft sensor||Measures the position of the camshafts||Often at the top of the head, near the crankcase cover|
|Fuel Temperature Sensor||Measures the fuel temperature||At the fuel rail or fuel line|
|Fuel Pressure Sensor||Measures the Fuel pressure||At the Fuel Rail/Pressure fuel line|
|Voltage Sensor||Measures the voltage||Often inside the control units|
|Nox Sensor||Measures the NOX in the exhaust||At the exhaust pipe|
|Exhaust temperature sensor||Measures the Exhaust Temperature||At the Exhaust Pipe|
|Boost pressure sensor||Measures the boost pressure||At the turbo pressure hoses/pipes|
|Throttle position sensor||Measures the angle of the throttle body||At the throttle body|
1. Coolant Temperature Sensor (CTS)
The coolant temperature sensor measures the temperature of the coolant. It is often mounted high in the engine compartment on a coolant hose or screwed directly into the cylinder head. In some vehicles, you may have several coolant temperature sensors. You often have a separate sensor for the cooling fan, and a separate sensor can be used for the instrument cluster and engine control module.
The cost of the sensor itself is not that high, but it may take some time to replace it, which can be a bit expensive if you have a mechanic do it for you.
If you want more information about this sensor, check out this article: Coolant temperature sensor
2. Intake Air Temperature Sensor (IAT)
The intake air temperature sensor measures the air temperature that flows through the intake pipes into the cylinders of your car. It is often integrated into your MAF sensor, but can also be mounted externally on your intake pipes, on the manifold or near the air filter box. If you have a turbo engine, it will most likely be mounted on the intake manifold.
The cost is often quite low, and replacement is most likely quite simple. To find more information about this sensor, check Intake air temperature sensor.
3. Mass Airflow Sensor (MAF)
The mass airflow sensor measures the air flowing into your engine. It often uses a hot wire that is cooled by the airflow, then converts the resistance into air mass flow and transmits the information to the engine control unit. You will often find the air mass sensor attached to your air filter box.
The cost of a new MAF sensor can be quite high, but replacing the sensor is often very easy.
4. A Manifold Absolute Pressure Sensor (MAP)
The manifold absolute pressure sensor measures the pressure inside the intake manifold. It can sense both under-pressure and overpressure. It is often used instead of a MAF sensor in American cars. If you have a manifold pressure sensor, you often do not need a boost pressure sensor.
The manifold absolute pressure sensor is most likely mounted on the manifold or on a vacuum hose from the intake manifold. The price of the MAP sensor is often low and replacement is often easy.
5. O2 Sensors (Lambda)
The O2 sensors measure the oxygen in the exhaust gases coming from the engine. Normally you have two or more O2 sensors. You have one in front of the catalytic converter and one behind it. The front sensor measures the oxygen and adjusts the fuel mixture. The rear sensor is only a diagnostic probe for the P0420 code. If you have a V-engine, you often have two O2 sensors per row (cylinders 1-3-5 and 2-4-6 etc.).
The O2 sensors are located on the exhaust pipe. The O2 sensors are often quite expensive and replacement can be difficult as they tend to rust and are difficult to remove.
6. Knock Sensors
The knock sensor monitors impacts or detonations from the cylinder combustion chamber. Detonations can cause severe damage to your engine and pistons, and to prevent this, the knock sensor is attached to your engine block. If it detects a misfire, it adjusts the ignition or fuel to ensure that the engine does not detonate.
Depending on your engine, you will often have one or more knock sensors. They are often attached directly to the engine block with a screw. The knock sensors are often cheap, but it can be a bit difficult to get hold of and replace them on some engines.
7. Crankshaft Sensor
The crankshaft sensor sends signals to the engine management system about the position of the crankshaft. The crankshaft sensor plays an important role in getting the right signal when it is time to ignite the injectors and ignition coil. A faulty crankshaft sensor can cause your engine to come to a complete stop, giving you rough starting conditions.
Depending on the engine, the crankshaft sensor is often located on the engine block, the transmission housing or the front pulley. The crankshaft sensor itself is often cheap, but can be difficult to reach and sometimes difficult to replace.
8. Camshaft Position sensor
The camshaft sensor measures the position of the camshafts. You often have a camshaft sensor on each camshaft. The sensor is used to measure the position of the camshaft so that the engine control unit knows in which position the engine is. The camshafts rotate 1 revolution when the crankshaft rotates 2 revolutions.
For this reason, a camshaft position sensor is needed to improve fuel economy. A symptom of a faulty camshaft sensor is often rough starting conditions. The camshaft sensors are often cheap and easy to replace, but on some car models, they are installed inside the timing belt housing and can be difficult to replace.
9. Fuel Temperature Sensor
The fuel temperature sensor measures the temperature of your fuel. Depending on whether the fuel temperature is high or low, it may differ in how much fuel is required for optimum combustion. The fuel temperature sensor sends a signal to the engine control unit to increase or decrease the amount of fuel required depending on temperature.
The fuel temperature sensor is most likely mounted on your pressurized fuel line, but in some cases it can also be mounted on the return line. The sensor can be quite expensive and is a bit messy to replace if you are not experienced.
10. Fuel Pressure Sensor
The fuel pressure sensor measures the fuel pressure on your fuel pressure line. It is most likely to be mounted on your fuel pressure rail, but sometimes it can also be mounted on the fuel pressure line or fuel filter. It is important to measure the fuel pressure, as an increase in pressure would result in a richer fuel mixture and a lower pressure would result in a leaner fuel mixture.
The sensor itself is often quite cheap, but it can be unwieldy to replace it if you are not an experienced mechanic. (A lot of fuel may leak out).
11. Voltage Sensor
A voltage sensor measures the voltage in the electrical system of your car. This unit is often integrated in the control modules and may not be replaceable. If you have a defective voltage sensor, you may need to replace the entire control unit in your car.
An ECU can often be very expensive and requires advanced programming to be installed in your car.
12. Nox Sensor
The Nox sensor measures the Nox volume in the exhaust gases. This sensor is not installed in many car models. Typically you can find them at Volkswagen, Audi, Seat, and Skoda. The Nox sensor is mounted on the exhaust pipe and on the control unit under a plastic cover.
The Nox sensor can often not be replaced without replacing the control unit. The control unit and the sensor are often very expensive and the replacement can be a bit tricky because the sensor tends to rust and get stuck.
13. Exhaust temperature sensor
The exhaust temperature sensor is often installed in diesel engines. It is used to measure the exhaust gas temperature before and after the particle filter, in order to optimize particle filter regeneration. Depending on the vehicle engine model you often have 1 to 4 exhaust gas temperature sensors.
The sensors are mounted on the exhaust pipe and on the exhaust manifold, and sometimes also on the turbocharger. The sensors are often quite expensive and can be difficult to reach and replace, they often rust and get stuck.
14. Boost pressure sensor
The boost pressure sensor measures the boost pressure in the pressure lines. You will often find this sensor if your car is equipped with a turbocharger or supercharger. You will find the sensor at any point on the pressure lines or on the intake manifold.
The boost pressure sensors are often cheap and can be easily replaced on most car models. On some car models, they can be difficult to access if they are mounted on the intake manifold.
15. Throttle position sensor
The throttle position sensor measures the angle of the throttle to see how hard you accelerate the car. On some car models the sensor is integrated into the throttle body, and you will need to replace the entire throttle body if it is defective. After replacing the throttle position sensor, you often need to make a basic adjustment.
The throttle body is often difficult to access, and if it is possible to replace only the throttle position sensor, the price of the sensor itself is quite reasonable. If you have to replace the entire throttle body, the costs increase considerably.
Hi, I’m Magnus, the owner and the writer of this website. I have been working with cars for 10 years, specialized in diagnostics and troubleshooting. On this blog, I’m sharing my knowledge and everything I know about cars. I hope you enjoy it!