I take my car to a school mechanic who is forever complaining how complex and complicated modern vehicles are and how difficult they are to work on. He gets misty eyes when he recalls a time when almost all vehicles were rear wheel drive and there were acres of space under the bonnet to swing wrenches and easily access whatever needed access.


What he fails to remember is the fault finding could be a real headache. Pre on-board computers, faults were much more difficult to find. Fine if a component just stopped working altogether, but intermittent problems could be challenging.

ECU’s and Sensors

On-board computers became increasingly common in the 80’s and 90’s. Bosch were amongst the pioneers of a computerised system. Known as Jetronic, this system was fitted to many cars in the 70’s, 80’s and 90’s, initially running the fuel system, they soon mushroomed in number and complexity.


From a mechanics standpoint, perhaps the most important evolution to come about in recent years is the expansion (in the number) of sensors to monitor mechanical systems. These sensors are responsible for continuously recording data and relaying this valuable information to the ECU.


The is of great benefit to the mechanic who no longer has to wrack his brains to figure out what is wrong with the vehicle – the ECU’s ability to store sensor trouble codes makes this data readily available.


In general, when a sensor detects a problem, it will create and store a trouble code in the ECU. A mechanic will perform a diagnostic scan of the vehicle and will find these stored error codes.  Once the mechanic has accessed and downloaded these codes, it is relatively easy to pinpoint the source of the code and complete the right repairs. The use of sensors has enhanced the capability and reliability of cars, but not all sensors are seen in every model. A bit later in this article, we will look at the most commonly found sensors.


As an aside, sensors also provide us as drivers with a plethora of useful information whether it is safety features like seatbelt reminders, blind-spot monitoring, tyre pressure monitoring, rain-sensing windscreen wipers or sheer convenience like park distance control.


I had a recent personal experience where my coolant temperature ran high. My vehicle immediately detected and warned me that the coolant temp was higher than expected. Within seconds, and amid much fanfare of flashing warning lights and loud beeps, my vehicle went into limp mode. Limp mode is a safety mechanism to protect your engine and transmission from further damage by, in my case, limiting the revs to 3000rpm and the automatic transmission to 3rd gear maximum.


I think the take-away point is that the multitude of sensors and the onboard ECU not only benefit the mechanic in pinpointing the problem. (Which it did. Armed with the fault codes, within 15 minutes the mechanic had identified the offending part, in this case - the oil cooler unit). They are also designed to save you from further damaging your car. 


In the very old days, the one’s my mechanic gets all sentimental about, I suppose the entire cooling system was represented by a lone engine temperature gauge on the dashboard. By the time the driver noticed it was high, I imagine the engine was already overheating and extensive damage had already been done. Then again, the driver could (albeit unwisely) choose to ignore the gauge and do even greater damage and seize the entire engine.

Common Sensors

While different makes and models make use of different sensors, there are some sensors which are commonly found across all modern vehicles. Below is a short list of some of the most common car sensors that you need to know about as a car owner or a car repair professional. They are important systems in the car and help notify you of anomalies in the car systems which require attention.

Mass Air Flow Sensor


The MAF or Mass airflow sensor is one of the essential sensors used in automobiles. This sensor is used in an engine of the car. This sensor can be controlled by a computer and can calculate the air density in the engine. If the working of this sensor halts, then the running of the vehicle will be stopped. In addition, the usage of petroleum will be high. These sensors are classified into two types namely vane meter & hot wire.


Engine Speed Sensor

The engine speed sensor in the automobile can be connected to the crankshaft. The main purpose of this sensor is to monitor the crankshaft’s rotating speed. So that fuel injection & the engine timing can be controlled. There are different ways for the vehicle engine to stop unexpectedly. So, this sensor will stop that for car drivers.

Oxygen Sensor

Located in the exhaust stream, usually near the exhaust manifold and after the catalytic converter, the oxygen sensor (or O2 sensor) monitors the content of exhaust gases for the proportion of oxygen. The information is compared to the oxygen content of ambient air and is used to detect whether the engine is running a rich fuel ratio or a lean one. The engine computer uses this information to determine fuel metering strategy and emission controls.


Spark Knock Sensor

The spark knock sensor is used to ensure whether the fuel is burning smoothly, otherwise, it will cause an unexpected ignition. This ignition is very dangerous which will cause damage in the engine of the car like damage of rings, head gasket, and rod bearings. Fitting these parts can be costly. So, this sensor is used to save all the troubles occurred in an engine of the car.


Coolant Sensor

The coolant sensor is the most significant sensor used in automobiles. Because the computer depends on the sensor inputs to control all the functions. For instance, turn ON/OFF the EFE system (Early Fuel Evaporation), retard, spark advance, the flow of EGR, and canister purge.

Generally, this sensor can be connected on the board. If the sensor is failed, then there will be some indications stalling, like poor fuel mileage, etc. So, the status of the sensor should be checked whether it is defective or not. If it is damaged, then it will be a problem.

Manifold Absolute Pressure Sensor

 The short term of the manifold absolute pressure is MAP. The main function of this sensor in an automobile is to monitor the load of an engine. Mostly, it measures the dissimilarity among manifold pressure. This can be received from the outside pressure by the car to make sure that the car engine is capable to receive petroleum depending on the changes within the pressure.

Fuel Temperature Sensor

The fuel sensor is used to check the temperature of the fuel continually whether the fuel utilization is optimum or not. If the fuel of the engine is cold, then it will take much time to burn due to its high density. Similarly, if the fuel is warm then it will take less time to burn. Here, the main problem is the inflow varying levels. So, this can injure other parts of an automobile. This sensor will monitor the petroleum is injected at the right speed and temperature. So that engine of the automobile works properly.


Throttle Position Sensor

The throttle position sensor in automobile mainly uses feedback carburetion & electronic fuel injection (EFI). It informs the computer regarding the throttle opening rate as well as the position of the relative throttle. This sensor is a variable resistor, which is used to change the resistance as the throttle opens.

It is not complex to identify the faulty throttle position sensor symptoms. As there is a fall while speeding up, then you can identify the faulty of the sensor. It is the major sign of a faulty throttle position sensor. Whenever you change this sensor, you cannot adjust it properly.

Vehicle Speed Sensor

As the name suggests, this VSS sensor has the capability to verify the speed of the car wheels. It is a type of tachometer. This sensor is arranged within the anti-braking system which is known as ABS. Additionally, the output of this sensor is also utilized for the odometer to read the speed of the vehicle to control gears depending on the vehicle speed.

Thus, this is all about the different types of sensors used in automobiles. These sensors are smart systems which are used for controlling different parts like coolant levels, temperature, the pressure of oil, levels of emission, etc. These automobile sensors are complex to allow a variety of values, decide and process the accurate combination. Here is a question for you, what is a parking sensor?

Camshaft Position Sensor & Crankshaft Sensor

The camshaft sensor, also known as the camshaft position sensor, works together with the crankshaft sensor to determine the exact position of the crankshaft. Electric signals from both sensors go to the engine management system and help control various variables such as fuel injection, ignition system timing and other engine parameters to ensure a smooth ride.