Your car’s engine knock sensor is in charge of detecting preignition and early detonation, that can potentially damage your engine due to the abnormal forms of combustion. Through loud knocking noises, pinging sounds, reduced engine performance, and poor fuel mileage, the signs of a bad knock sensor can prevent this issue from permanently damaging the engine.
What is a knock sensor?
When you step on the gas pedal in your vehicle and you hear a slight noise coming from the pedal or the engine, this is what an engine knock is. Hearing this “engine knock”, along with extra engine noise and the exhaust note, this is a key sign of engine knock and can cue the knock sensor. What you are hearing when this happens is pre-ignition, which generally occurs when there is a pocket of the air and fuel mixture that is igniting before the flame is occurring from the spark plug.
If this happens in your car, then there is a small electrical current that happens near the explosion, increasing the pressure within the cylinder. In most cases, the engine knocking can lead to severe damage in the engine, causing an expensive repair or replacement, and meaning that the bad knock sensor can damage the engine.
In an older engine where the ignition timing can be changed to fit your needs, the engine knocking can be analyzed and fixed by slowing down the timing just a little. In addition, water injection could be a potential solution.
Symptoms of a bad knock sensor
When engine knock occurs in your vehicle, the knock sensor is in charge of keeping your engine in good shape and preventing a bad knock sensor from damaging the engine. Engine detonation occurs during the internal combustion process if the fuel in your car’s cylinder episodes too early and changes the ignition timing to a faulty time. This detonation that occurs too early is often referred to as engine knocking.
When a vehicle’s engine starts up and begins revving while you are driving, detonation occurs. There is a knock sensor that is in charge of regulating the engine, detecting the vibrations and the detonations and sending the correct voltage signals to the powertrain control module. This can alter if a bad knock sensor can damage your engine.
A powertrain control module is in charge of controlling a vehicle’s engine, transmission, and other specific driveline components that are crucial on the make and model of your car and can vary depending on what type of vehicle you have. Generally called the PCM in your vehicle, this automotive control unit combines the engine control and the transmission control unit.
After the powertrain control module has determined the signal produced from the knock sensor, the module will then change the ingiiton’s itming and prevent early engine detonation. This can help prevent the engine from gaining further damage and needing a repair or replacement. This shows how a bad knock sensor can damage the engine. If your knock sensor were to malfunction or become damaged in your vehicle, there would be clear symptoms that a drive and passenger would notice.
Engine warning light
One of the first symptoms that is the most visually noticeable for the driver to see when determining the healthiness of your engine and knock sensor is the engine warning light coming on. You might notice this show up on your engine dashboard. Although this can happen due to many reasons, one of the main reasons of hte engine warning light coming on is a poor knock sensor.
Other reasons that an engine warning light may come on are varied depending on the root of the cause. One of the main reasons is the oxygen sensor failure, which measures the amount of unburnt oxygen in a car’s exhaust system, sending data to the vehicle's computer and regulating the mixture of fuel and air that enters the cylinders.
Another cause of an engine warning light coming on besides a bad knock sensor that can ruin your engine is a loose fuel cap, which is a crucial part of the fuel delivery system that prevents fumes from leaving the fuel tank.
Furthermore, a catalytic converter failure, that is integrated into the vehicle's exhaust system, generates carbon monoxide into carbon dioxide, and can be a crucial part to the check engine light coming on. Any of these reasons could be the culprit, although a bad knock sensor can damage your engine and be the main reason for the engine light coming on in your car.
When the knock sensor starts to malfunction and becomes damaged over time, you may hear loud sounds that come from underneath the hood in your engine that can resemble loud thumping sounds. The longer you go without fixing the root cause of this issue, the louder rehse sound will get and will increase while you are driving.
The reason these noises occur is mainly due to the timing of the ignition of the air and fuel mixture located within the cylinder. Usually in a normal car with a properly working knock sensor, this mixture would reach the combustion point too early. Sounds like this should spur you to immediately take your vehicle to the mechanic so that no further problems arise.
Poor Fuel Mileage
If you realize that you are getting fewer miles per gallon than you normally do in your car with the same amount of uel in the tank, then your knock sensor could be damaged or malfunctioning, with the bad knock sensor potentially harming your engine. Even so, there are many other reasons that you could be getting bad fuel mileage.
The other popular causes of poor fuel mileage and bad fuel economy in your vehicle can be for many different reasons. One of these main causes besides a bad knock sensor that can damage your engine is incorrect tire pressure, being the easiest to correct. The second reason is spark plugs, with these important parts misfiring or performing poorly and negatively influencing your gas mileage.
Furthermore, a bad oxygen sensor or air filter can reduce gas mileage by 20%, since they are unclean and could be clogged with sand and debris. Similarly, bad fuel injectors can cause less gas mileage, since they are directly responsible for the passage of fuel into the engine. Despite a bad knock sensor damaging the engine, these other reasons could be a potential cause for poor fuel mileage.
When you press on the gas pedal to try and speed up your car while you are driving, and you notice that the acceleration does not happen quickly or like it normally does, then a bad knock sensor could be the root cause of preventing the acceleration from being effective. If you combine this symptom with the previous three, then you can be almost positive that a bad knock sensor is the cause and can damage your engine.
Reduced Engine Performance
The worst and most severe symptoms that you might notice from the bad knock sensor will typically happen when the internal engine components become damaged or break down over time. If you have let hit problems get worse over time without fixing the bad knock sensor or any of two ther engine parts, then your vehicle will start to suffer, with an increasing drag and the car jerking while accelerating.
You might even notice a burning odor or smell coming from the engine and getting into the cabin of your vehicle, that can be easily smelled by both the passengers and the driver. If you continue driving your vehicle, then this could result in the bad knock sensor and the poor engine components causing the entire engine being destroyed and requiring a replacement.
An engine replacement cost is one of the most expensive repairs or fixeds you can have in your vehicle, no matter what kind of make, model and year of vehicle you have. Replacing an engine actually often 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 4 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.
Knock Sensor Replacement Cost
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 economy vehicle, the average knock sensor replacement cost will usually range anywhere between $120 and $500 for replacing the sensor. The parts cost will be between $65 and $200, while the labor cost will range between $50 and $350.
In most situations, the parts cost and the labor costs will actually be pretty equal, with both of these averaging around the $100 mark. If you can find a good deal on spare parts that are used or from independent shops, then this could lower the overall replacement cost, since you will be saving money on the parts cost.
Can I drive with a bad knock sensor?
After seeing the symptoms of a bad knock sensor and seeing how the bad knock sensor can detrimentally affect your engine and the performance, you might be wondering if you should drive on a bad knock sensor, or if it is even possible to drive with a bad knock sensor.
The short answer is, yes. Once the function of a knock sensor is shifted, you will begin to experience the drawbacks of a poor knock sensor, like reduced engine performance and low fuel mileage. We know that this component is very important because it works with your car's computer and powertrain, detecting sounds from underneath the hood or vibrations that occur due to premature engine detonation.
When this occurs in your vehicle, these small vibrations that consistently happen will be caught and the knock sensor will deliver a voltage signal to the timing of the ignition. Basically, the knock sensor is in charge of making sure that your engine works properly and protects the engine from any harm or further damage.
Now that you know how important the knock sensor is with the engine performance and longevity, you might need to know the danger of driving with a bad knock sensor. Once the knock sensor is breaking down, worn out, or damaged, a dip will occur every time you go and accelerate your vehicle. The inner side of the engine will get hotter, and get hotter quicker, since there will be a malfunction with the emissions production.
The engine overheating can be due to increased friction, which can cause the engine damage. There are other reasons for the overheating engines, like too little or no coolant, driving without proper levels of antifreeze, coolant leaks, broken water pumps, radiator issues, the oil being too low, the thermostat failure, issues with belts and hoses, and the heater core is plugged up.
In addition to your engine overheating and the inner side of hte engine getting hotter due to other emission production, the output of your car will not work like it should. However, instead of thinking about whether you can drive your car with a bad knock sensor, it will be better to make sure that the brake and knock sensor are functioning correctly in order to keep your car safe and prevent the potential for any accidents.
In the more extreme cases in your vehicle, a bad knock sensor can damage your engine. This is the last thing you want to occur, since a damaged engine can lead to an expensive repair or replacement. The cost to buy a new knock sensor is much more affordable than an entire engine.
If you get to this point and you might need an engine replacement due to the bad knock sensor damaging the engine, the engine replacement might not actually be worth the cost. The cost of a car repair might not be worth the price you will have to pay to get your car safely back on the road without you worrying about a performance decline. There are a few key things to think about when determining if you should replace your engine.
The first would be if you can fix the car problem yourself. If you can fix the bad knock sensor yourself or get the used parts on your own, you can reduce the overall bad knock replacement by half. If you have the knowledge to replace the engine on your own, then this could also save you thousands of dollars. However this fix is much more complicated and is much more detrimental to your vehicle if done wrong, so it is very rare that a car owner would be able to do this without a mechanic there.
Next, you need to consider the cost for the engine replacement. A bad knock sensor replacement is not very expensive, but an engine replacement is $4,000-$5,000 to replace a 4 cylinder engine. This is oftentimes too much money for a car owner to pay, especially if your vehicle is older, already used, damaged, or will not sel for a lot on the market.
Lastly, you need to realistically assess your vehicle’ worth. Do you think that your car is worth repairing, or do you think that you would be better off selling your car at a local and reputable junk car buyer? We think you should try Cash Cars Buyer if you do not want to pay for the bad knock sensor replacement, or if your bad knock sensor has damaged your engine beyond repair!