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Knock Sensor Function

Abhijit Naik
Being well-versed with the function of knock sensor will tell you exactly why you need it in your vehicle.
Engine knocking is one of the most hazardous attributes of a vehicle, which is known to result in loss of power and cause severe damage to the engine. It occurs as a result of ignition of fuel and air within the cylinder before the actual moment it was supposed to occur.

Why Use Knock Sensor?

According to the experts, operating a vehicle near the detonation (i.e., ignition of fuel and air with the help of a spark from spark plug) limit helps in producing more power and adds to the performance of the vehicle. That being said, there is a thin line of difference between operating a vehicle near the detonation limit and crossing this limit.
Like we said earlier, operating a vehicle with knocking engine can result in some serious damage to the engine and therefore, the engine has to be monitored for the same. This is where a knock sensor comes handy. Simply put, it helps you monitor engine knocking and indirectly helps you keep all those knocking-related engine problems at bay.

Functions of the Knock Sensor

A knock sensor is a low voltage producing device which detects harmful engine vibrations in the vehicle and alerts the on board computer to take necessary action. This, in turn, helps you drive the vehicle at peak of advanced engine timing, without having to worry about causing any damage to the engine as a result of excessive knocking.
The sensor generates electrical charge when it detects abnormal vibrations in the engine of the vehicle. It is specially designed to record faint vibrations with the sound of engine in the backdrop.
When excessive knocking is recorded, the sensor sends electric signals to the on board computer of the vehicle, which, in turn, reduces the speed of the engine automatically.
As the engine speed is lowered, the rate at which the spark plug fires is lowered and knocking is eliminated. The computer continues to keep a track of the signals sent by knock sensor throughout the process and brings the speed of the engine back to normal when knocking is completely eliminated.
The placement of a knock sensor plays a crucial role in its functioning. Ideally, it has to be placed in between the cylinders, as this will ensure that misfiring in either of the cylinders will be recorded promptly. In several cars with advanced engines, more than one units are used, which makes the task of detecting knocking easier.
Like various other components of the vehicle, even knock sensors are prone to excessive wear and tear, which can render them useless after a specific period. In such circumstances, you may have to replace it to ensure smooth functioning of the engine.
In a vehicle with worn out sensor, you may observe abnormally high knocking―the sound of which will be louder than the sound of the engine itself.
On an average, a knock sensor will cost you in the range of $50 - $200, while the replacement cost will depend on a range of factors including the model and where you go to fix the problem.
That may seem a bit costly, but you need to understand that it can save a significant amount of your money, which you would have to otherwise spend on a damaged engine.