The heart of your vehicle's engine management system - that's what your car's knock sensors are. Knock sensors enable your vehicle to achieve the maximum combination of fuel/air mixture and timing to increase power and efficiency generated. The general aim is to waste less gas and save more money. With the increasing prices in today's market, it is vital to get a quality car knock sensor or auto knock sensor and get your money's worth.
Knock sensors manage the way your car burns fuel. It is vital to get the specific knock sensor for your type of vehicle (such as family or high performance car) demands. When inspecting a knock sensor, you have to make sure there is no corroded terminal or there is no damage of the wires and connections.
Beware of faulty knock sensors. Not only do such lessen your car's performance and fuel economy, they can also cause expensive damage to your beloved engine. Faulty knock sensors can actually cause up to thousands of dollars in damage if not immediately replaced.
Knock Sensor Buyer’s Guide
The knock sensor is a small device that warns your car’s powertrain control module (PCM) when your engine is in bad shape.
Knock sensors are meant to detect engine knocking which occurs when the timing of combustion is off.
The main task of knock sensors is to send a signal to the PCM which corrects the ignition timing by retarding or advancing it.
Vibration detection sensors can be an inductive resonant, piezoelectric resonant, or piezoelectric non-resonant.
The knock sensor is often affected by temperature, surges in voltage, mechanical shock, and many more.
Symptoms of a failing knock sensor include an illuminated check engine light, persistent knocking noises, poor fuel economy, and lack of engine power.
You can buy an OE knock sensor replacement from the website for as low as $1, while high-quality options could range up to $1,200.
A lot of car owners tend to overlook small components in their cars. The engine alone has over a hundred parts, and more than 40 of those are actual moving parts. Hundreds of parts are found all around the car, both mechanical and electronic. Small parts like sensors help your car’s computer to accurately make adjustments depending on the status of your engine, which is why they are very important.
There are at least 10 sensors found inside a modern car, each of these is responsible for monitoring a specific function. For example, an oxygen sensor measures the proportion of air and fuel in the exhaust gas. Another sensor that is crucial to your car’s engine is the knock sensor. Here are the important things you need to know about knock sensors.
What is a knock sensor?
The knock sensor is a small device that warns your car’s powertrain control module (PCM) when your engine is in bad shape. The PCM uses the signal from the knock sensor to alter the ignition timing and avoid detonation. You can find it on the engine block, near the intake manifold, or on the cylinder head. Some cars have the knock sensor inside the engine which makes it very difficult to access. If that is the case for you, you’ll need to take off the cylinder head to have a clear view of the knock sensor.
What does a knock sensor do?
These devices are called “knock sensors” because they are meant to detect engine knocking. Engine knocking occurs when the timing of combustion is off. The causes of this anomaly range from a faulty spark plug to a carbon build-up (gunk) inside the cylinders. Engine knocking, as its name suggests, is characterized by knocking noises due to excess detonation in an ignition cycle.
Detonation or pinging, which is synonymous with knocking, could introduce more serious problems to your engine if left unresolved. The main task of knock sensors is to send a signal to the PCM when it senses a knock. The signal is then used to correct the ignition timing, either by retarding or advancing it.
What are the different types of knock sensors?
Knock sensors detect detonations in two different ways. This could be either through vibration detection or pressure management. Vibration detection sensors can be an inductive resonant, piezoelectric resonant, or piezoelectric non-resonant.
Both the inductive and piezoelectric resonant sensors feature a vibration plate that has the same resonant frequency as the vibration from an engine knock. This vibration plate converts the knock vibration into an electric signal through the piezoelectric effect. The piezoelectric effect is a material’s ability to generate an electric charge when mechanically stressed.
This type of sensor relies on a spring-mass system to measure vibration. Spring-mass systems help the sensor to directly measure the vibration and have bandwidths ranging from 5 kHz all the way to 15 kHz. Non-resonant sensors can detect knock far more efficiently than resonant sensors. The vibration plate of resonant sensors can only work if the vibration of the knock is at the same frequency. This could be a problem since knock vibration frequencies vary.
What causes a knock sensor to go bad?
Sensors are electrical devices meant to detect an issue and send a signal to your car’s computer. Electrical devices are often affected by temperature, surges in voltage, mechanical shock, and many more. The knock sensor is no exemption. It could easily go bad when one of these happens. If you suspect a failing knock sensor, you may test it by attaching a device like an oscilloscope to the wire connecting the computer to the sensor. An oscilloscope is a device that looks like a heart rate monitor that is used to test an electrical device in your car.
Symptoms of a bad knock sensor
Illuminated Malfunction Indicator Lamp (MIL)
The number one symptom you are likely to find is an illuminated MIL or Check Engine Light. This is the engine icon found on your dashboard’s instrument cluster that is meant to light up as soon as it detects problems concerning your engine. This means any problem that can potentially affect your engine can trigger the warning light. One of the possible causes is a bad knock sensor. The computer will turn this warning light on when the signal from the knock sensor fails to reach it.
Persistent engine noises
You shouldn’t hear knocking noises if your knock sensor is in good shape. Thumping noises coming from the engine are clear bad sensor symptoms. Keep in mind that if the knock sensor can’t send signals to the PCM, the engine will keep running inefficiently. This could lead to more serious problems, including permanent engine damage.
Gasp in power
If you start noticing that your engine is gasping for power, especially during acceleration, chances are there’s an extreme case of detonation inside the chambers. It’s likely that the air and fuel mixture is not being burned properly due to a malfunctioning knocking sensor. Without the sensor’s data, the PCM won’t be able to intervene with the ignition timing and combustion rate to make your engine run smoothly.
Compromised fuel economy
You should know that ignition timing is crucial in maintaining a healthy fuel economy. Timing can be compromised if the ignition is over-retarded, which means the ignition spark is significantly delayed. Compromised ignition timing results in poor fuel economy.
How much is an OE knock sensor replacement?
If you’re in the market for a knock sensor, CarParts.com has the right part for you. You can buy an OE knock sensor replacement from the website for as low as $1, while high-quality options could range up to $1,200. OE knock sensor replacements are sold as a single piece, in sets of two and four, or as part of a kit.
To find the right knock sensor, input your vehicle’s year, make, and model on the filter tab of our website. You may also select the brand or series you prefer, as well as the price range of the product you’re looking for. All knock sensors listed in CarParts.com’s catalog are of high-quality and only come from reputable parts manufacturers in the market.
Important Facts You Need to Know About Knock Sensor
Detect poor engine performance before it causes full auto breakdown. Use only a trusty Knock Sensor or a quality Knock Sensor Replacement.
"Absolute power corrupts absolutely." Simply put, this means that having too much power isn't good for you. On the other hand, having too little of it isn't good either, especially when it comes to your car. And since you need your car to maximize power each time you drive, it's important that it doesn't fall short. One way to keep track of your car's power statistics is to equip it with a Knock Sensor.
This component helps you detect whether your engine produces the power you need or not. It's mounted on your engine and is responsible for informing your engine's computer if your cylinders are knocking. Knocking occurs when there is an increase in cylinder pressure. This increase is caused by the pre-ignition of the air-fuel mixture. Once this happens, pressure waves in the combustion chamber hit the cylinder walls, which cause a knocking sound. A number of problems can cause your cylinders to knock. It can be caused by the use of low octane fuel, overheating, or advanced timing. Aside from ensuring that you get the power you need, knock sensors also allow you to make engine adjustments for better fuel economy.
Without the right amount of power, you'll find it difficult to maneuver, especially when you need to increase speed or you need to go uphill. And the best way to ensure that you consistently get the right amount of power is by installing a Knock Sensor. That way, your engine won't fall short of your expectations.
Getting the Proper Knock Sensor for Your Ride
Your vehicle also upholds the motto that prevention is better than cure. This is proven by the part that is called as the knock sensor. It is connected to your vehicle's computer system in order to determine and serve as a warning signal against engine knocks. This occurs when the spark plug fails to trigger the fuel operations properly. As a result, your engine cannot run smoothly. With your knock sensor, the first sign of engine trouble can be avoided. However, it can wear out over time. Hence, you need to have a replacement. Here are important things that you must keep in mind if you are about to make a purchase for a new knock sensor.
Different types of knock sensor
Whether you love driving off-road or on normal paths only, there are two types of knock sensor that you can pick from:
- Broadband single wire sensor: This is the older type of knock sensor in the automotive market. It works by observing and identifying the standard range of engine noise from its operations. Once the broadband single wire sensor detects a noise that is higher than the usual, it will send a signal to your vehicle's electronic control unit (ECU). This type of knock sensor can be able to detect a huge variation in the rates of the engine noise. It also has electromagnetic resistance so that it can function smoothly.
- Flat response two-wire sensor: This second type of knock sensor is the newer design introduced. Its difference from the broadband single wire is that it already has a programmed range of engine noise frequency. If there is an engine knock, the flat response two-wire sensor will respond by giving out a higher voltage than the predetermined frequency range. As a newer type of sensor, it is more accurate than the broadband single wire.
Other things to consider
Both types of sensors has the same piezoelectric element that allows them to send signals to a vehicle's electronic control unit (ECU). However, you must pick which type is compatible with the ECU of your vehicle. Some knock sensors that are available in the market come in a complete assembly, while others come in a single item only. It still depends on your driving needs.
How to Replace Your Knock Sensor
Imagine what would happen if there is no signal that can tell how knocked up the engine is. You would probably end up driving recklessly. That is why your knock sensor is up to the rescue. It is responsible for detecting the signs of engine detonation. The knock or detonation is harmful in a way that the spark plug will not be able to ignite fuel in the right manner. This further causes the engine to sputter, and can also lead to more serious engine problems. So thanks to your knock sensor, the possible damage can be prevented. But if your knock sensor fails to maintain its optimum working condition over time, it is best to have it replaced with a new one. These steps can help you to install your new knock sensor efficiently:
Difficulty level: Moderate
Things you'll need:
- jacks and jack stands
- dielectric grease
- new knock sensor
Step 1: Before you remove your knock sensor, you need to raise your vehicle with the help of jack stands to have proper access on the front area of the engine.
Step 2: As a safety measure, it is recommended to disconnect the negative battery cable from the terminal.
Step 3: Once you have located your knock sensor, you must unplug its wiring harness connector first before totally removing it. This will ensure that its electrical connections will not be affected throughout the process.
Step 4: Look for the hexagon-shaped part of your knock sensor. Once you have located it, slide a wrench onto it in order to unbolt your knock sensor in a counterclockwise motion.
Step 5: Before attaching your new knock sensor on the engine block, you must apply a dielectric grease on its threads for lubrication.
Step 6: Install your new knock sensor, and tighten it securely with the help of a wrench.
Step 7: Reattach the wiring harness connector and the negative battery cable to the terminal.
Step 8: Remove the jack stands that support your vehicle while lowering it carefully in order to test the efficiency of your new knock sensor.