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What Does A Knock Sensor Do? – What There is To Know!

What Does A Knock Sensor Do? – What There is To Know!

By figuring out the knock sensor’s main function, the symptoms of a faulty knock sensor, and the causes of the damaged knock sensor, you can help answer this elusive question. You will soon discover that this part has a very important role in your vehicle. 

Auto Repairs Are EXPENSIVE

What is a knock sensor?


When you press on the gas pedal in your vehicle and hear a soft noise coming from the pedal or the engine, “engine knock.” Hearing this loud knocking or clunking sound and additional engine noises is the main sign of engine knock. These sounds can alert the internal computer to turn on the knock sensor. When this happens, you hear pre-ignition, which typically occurs when there is a pocket of the air and fuel mixture lighting and igniting before the flame comes out from the spark plug. If you are wondering what a knock sensor does, this can help answer your question. ,


  • Knock Sensor Function



If this happens in your car, a small electrical current goes off near the explosion, increasing the cylinder’s pressure. In most cases, the engine knocking can lead to severe damage in the engine, causing an expensive repair or complete replacement. When wondering “what does a knock sensor do?” keep in mind that a bad knock sensor can damage the engine and lead to a high knock sensor cost. If you are wondering how much it cost to replace a knock sensor, the answer is a LOT.

Altering Ignition Timing


In an older engine where the ignition timing works with your needs, the engine knocking can be analyzed and fixed by slowing down the timing. In addition, water injection could be a potential solution. By figuring out the engine knocking issues’ solution, you can successfully lower the total cost to replace a knock sensor. When wondering, “what does a knock sensor do?” you can already tell that this part is crucial to the functioning of your engine’s timing. 


At high engine speeds, the control module is in charge of turning on the ignition timing, allowing the air to fuel mixture in the engine time to burn and combust at the right moment. However, if the ignition time is too delayed during the combustion process, it could lead to pre-ignition and pre-combustion. This uncontrolled engine ignition is also known as engine knock. The pre-ignition or pre-combustion leads to a high cost to replace a knock sensor.

Delaying Spark Timing


In order to prevent premature vibrations and explosions from happening in your car, the knock sensor is in charge of detecting the vibrations from the pre-ignition, sending a signal to the electronic control module, and delaying the timing of the spark to avoid the detonation. 


  • What is an “Engine Knock”?



Under normal driving situations and performance qualities of the car’s engine, the engine control unit is in charge of triggering the spark to ignite the air to fuel mixture within the engine’s chamber. Since the air to fuel mixture takes a certain amount of time to burn adequately, the engine control unit adjusts the ignition timing to provide a balance of both the power and efficiency. Determining what the engine knock is in your vehicle can help you answer the question of “what does a knock sensor do?”


Any delay in the spark of the ignition timing can result in a decreased power and cue the engine knock to occur. Any advancement would cause self-ignition within the chamber and can damage the engine, leading to an eventual engine replacement that can be very expensive. 

What Causes a Knock Sensor to go Bad?

There are various reasons why your car engine knock sensor might go bad over an extended period. There are many solutions and root causes as to why you might have a failing or damaged knock sensor. Knowing the cause can help you figure out the answer to “what does a knock sensor do?” 


  • Check Engine Light



The first reason for a damaged knock sensor could be the illumination of the Check Engine Light. If the computer does not recognize the sound in your vehicle, it can automatically turn on the check engine light. Although this can come on for numerous other reasons, like a loose fuel cap, catalytic converter failure, spark plug issues, ignition coil damage, or bad spark plug wires, the engine light won’t turn on from the abnormal sounds. 


In this case, you should bring your cat to a mechanic to evaluate the cost of replacing a knock sensor. When determining the knock sensor’s value, the mechanic can help you answer the question, “what does a knock sensor do?”


  • Misuse of the Vehicle



The second cause of a bad knock sensor could be the misuse of the car – if you are handling your vehicle roughly and causing poor acceleration and poor fuel economy, the car's performance will suffer, and it can damage the knock sensor. It can even go bad if you are removing the knock sensor in the wrong way. If you push the connectors the wrong way, the sensor can go out of alignment and break fragile parts. 


Signs of a Bad Knock Sensor


As we know now, the car’s knock sensor is located on the intake manifold, the cylinder, or the engine block. The engine knock sensor’s purpose is to diagnose unusual pulsations and abnormal combustion caused by the improper timing of the engine detonation. When wondering, “what does a knock sensor do?” this part is basically in charge of the car’s computer and the ears of the vehicle, determining if the engine is working correctly.


It is vital to know the signs and symptoms of a faulty knock sensor to see the importance of this part in your car.  


  • Engine Feeling Wrong



The first symptom is that the engine performance does not feel right, and the abilities of the engine don't feel correct while driving at high speeds or while the vehicle is towing a heavy load or accelerating uphill. Luckily for you, when asking, “what does a knock sensor do?” you can determine that the knock sensor and engine go hand-in-hand.


If you notice that something seems wrong with your vehicle’s handling and performance, then it is best that you should bring your car to the mechanic. Even if no check engine light goes on, you should still bring your car to a mechanic.


  • Poor Acceleration



A bad knock sensor could also cause the engine to not accelerate correctly and at the right moment, not providing enough power while driving on the highway, and lowering the overall fuel mileage, efficiency, and the economy of the car. If you notice that this is happening when you are driving your car, especially at highway speeds, you should have your car brought to a certified mechanic to see why your car is slow to accelerate.


There are other reasons why your car could be slow to accelerate besides a bad knock sensor. Other symptoms and causes of why the knock sensor causes the car to be slow to accelerate is a bad or clogged fuel injector. Fuel injectors can be blocked due to contaminants within the fuel and must be very precise in controlling the amount of power.


However, keep in mind that when wondering, “what does a knock sensor do?” that one of its primary functions deals directly with the acceleration of your car. Knowing this can help you diagnose the acceleration problems you are having. 


  • Check Engine Light 



In addition to the slow acceleration and the engine not feeling right, a bad knock sensor can cause different sounds being produced in the car’s engine. If the computer does not recognize a sound being produced by the car, it will turn on the Check Engine light


A check engine light can also come on for various reasons like your oxygen sensor fails, a loose fuel cap after you put gas in your tank, catalytic converter failure, spark plug problems and ignition coil issues. 


In addition, the check engine light can turn on due to  bad spark plug wires, mass airflow sensor failure, issues with an aftermarket alarm, or a vacuum leak. However, when wondering “what does a knock sensor do?”, now you know that the knock sensor works in tandem with the check engine light and the internal computer. 


  • Car Losing Power



Once your car’s computer detects that the engine knock sensor is not working correctly and is malfunctioning, your vehicle will most likely lose power – and this can sometimes happen while you are driving, which can be very dangerous. How much energy you lose in your car can depend on the octane limit of the engine, and how heavily it relies on the knock sensor input. 


  • Engine Replacement



An engine replacement cost is one of the most expensive repairs or fixes you can have in your vehicle, no matter what kind of make, model, and year of the vehicle you have. Replacing an engine costs more than a vehicle's overall worth is for the owner. On average, the replacement cost is between $4,000 and $5,000 to replace a four-cylinder engine. 


The price is even likely to increase on a V6 or V8 engine, meaning that a high-end, luxury, or sports-oriented car can be upwards of $6,000 for an engine replacement. A faulty knock sensor can lead to an engine replacement if you are not careful. The importance of the knock sensor shows how, when asking, “what does a knock sensor do?” you can see it has many important functions. 

Knock Sensor Replacement Cost


In most cases, with your vehicle and when your car is running at an optimal level, if you leave the engine knock alone and do not take care of the root issue, it can lead to permanent damage. This quickly will lead to engine breakdown and the need for an engine replacement. 


This can cause the car to be unable to accelerate smoothly, the car to start to jerk while driving, the car to stall, and the car to drag. Preventing the knock sensor from going bad can also help you answer the question “what does a knock sensor do?”. As you will see all of the imperative functions that this part does in your car.  


These signs can also be accompanied by a burning smell that can be very noticeable by both the driver and the passengers. These are sure signs that the engine knock sensor can detect permanent engine damage. 


  • Average Price



The bad knock sensor can damage an engine if you do not replace the part and if the faulty knock sensor has damaged other components. However, unlike an engine replacement, the good news is that you will not have to pay nearly as much to replace a bad knock sensor. If you have a standard vehicle, the average knock sensor replacement cost will usually range anywhere between $120 and $500 on average for the cost to replace a knock sensor. 


  • Labor and Parts



The cost of the parts is generally between $65 and $200, while the labor cost will range between $50 and $350. 



Knowing the answer to “what does a knock sensor do?” can help you determine the importance of this part in your vehicle. Seeing the symptoms of a faulty knock sensor, what causes the knock sensor to go bad, and the overall replacement and repair cost can give you an idea of the main function of this mechanism in your car.