Common Symptoms of a bad Knock Sensor and Replacement Cost

There are many sensors in every automotive engine used for regulating things like temperature, emissions, and ignition timing. One of these sensors is known as the ‘Knock sensor.’ The term Knock can be ascribed to detonation, pinging, spark knock, or pinking. The knock sensors are usually located on the intake manifold, head cylinder, or engine block. It is a listening device that enables your car computer to detect noise and vibrations caused by engine knock.

If your engine longevity is important to you, you want to listen to vibrations and knocking happening inside your engine. Hence, you should be able to identify symptoms of a bad knock sensor.

Symptoms of a bad knock sensor

A lousy knock sensor can cause severe engine damages if not detected and replace on time. So, if you notice any of the following signs, you want to seek professional advice.

what causes a knock sensor to go bad

Check Engine Light: One of the first symptoms that will indicate a lousy knock sensor when giving concern about your engine’s healthiness is the check engine light popping up on your dashboard. You might see this light on your dashboard. However, several factors could cause the check light to display on your dash. One of these reasons is a faulty knock sensor.

Other reasons why the engine warning light may display on your dash depend on the fault your vehicle engine is encountering. One of these reasons is a bad O2 sensor, which monitors the amount of unburnt 02 in the exhaust system, regulates the fuel-air mixture that enters the cylinder walls, and reports data to the car computer. Another reason this light might come up beside the lousy 02 sensor and faulty knock sensor is a loose gas cap, which helps prevent fumes from escaping.

In addition to these causes, a clogged catalyst converter in your exhaust system turns carbon monoxide into carbon dioxide and can be the reason behind the warning light. The engine warning light is generally the first visual and noticeable symptom of bad knock sensor Honda Accord or any other car make and model. In all, a lousy knock sensor can damage your entire engine if ignored.

Loud Sound: When the knock sensor starts malfunctioning and eventually goes wholly bad, you will hear a bad knock sensor sound. What sound does a bad knock sensor give? A lousy knock sensor will deploy a loud thumping sound in your engine. The longer you drive without solving the cause of the sound, the louder the sound becomes. These sounds occur within the cylinder walls due to the timing of the ignition of the air-fuel mixture.

Poor Acceleration: If the knock sensor goes faulty, it’ll no longer aid the ECU resulting in low engine performance. Therefore, the car will suffer from poor acceleration. Because the Pressure generated in the combustion chamber is just a part of an engine capacity, the torque is lower, and your car will have acceleration issues. Poor acceleration is a common symptom of bad knock sensor Hyundai.

Low Gas mileage: Many factors can cause reduced gas mileage; however, if you notice reduced gas mileage in addition to any of the outlined signs in this article, you should have a professional inspect your knock sensor. The knock sensor might have to blame. When the ignition timing is insufficient, it can cause unnecessary knock or ignition resulting in lower gas mileage.

Reduced Engine Performance: The most noticeable symptoms of bad knock sensor Ford that you will notice might be when your internal engine components damage or break down over time. If you have seen the symptoms of bad knock sensor 5.3 and ignore it, shortly, you will start experiencing poor acceleration, misfiring, jerk, and drags.  In some cases, you might begin perceiving a burning smell. The smell may be strong enough that both the passengers and driver will notice it. If you continue driving your vehicle at the state, you might damage your entire engine, and you’ll need to replace it.

The engine of a car is one of the most expensive parts you can find in any vehicle regardless of the make, model, and vehicle year. Replacing an engine sometimes can be higher than the vehicle’s overall worth. On average, the cost of a new engine would be $2,000 – $4,000 for a four-cylinder engine. The price can go above $4,000 if your car has a V-type engine. The actual price solely depends on the car make, model, year, and the dealership you want to get the engine.

Symptoms of bad knock sensor

Frequently asked questions (FAQs)

Can a bad knock sensor cause knocking?

Yes, a bad knock sensor can cause severe knocking on your engine. A few days ago, I diagnosed a Lexus LX570 model and got faulty code P0325. Before the diagnosis, the car idles quietly, and if I engage the gears, the car will give a heavy knocking. The knocking was much that I thought something more serious is wrong. When I replace the knock sensor, the noise stops instantly.

Is it easy to replace a knock sensor?

On some cars, replacing a faulty knock sensor can be pretty straightforward. You might not have to lose many things on the engine before accessing it. However, replacing a lousy knock sensor on most newer cars can be a pain in the neck. You will have to take off several engine components before accessing it.

What happens if I don’t replace my knock sensor?

A knock sensor is there on your engine to detect engine noise caused by pre-ignition. This is to enable your car computer to advance the ignition timing without allowing the engine to ping. This will give you optimum operating engine power and fuel mileage. If the knock starts malfunctioning, the engine could begin igniting, and the car computer might not detect it. The pinging can cause severe issues like blowing holes on the Piston or even cause the combustion process to burn. If a knock sensor goes completely bad, you’ll experience loss of fuel mileage, hesitation, and reduced power.

What causes code P0325?

P0325 is an OBDII trouble code that indicates a lousy knock sensor malfunction (Bank1, sensor 1). This trouble code tells that your knock sensor is faulty and needs to be checked and replaced.

What does a knock sensor do?

The knock sensor detects pre-ignition and detonation happening inside the engine block. Though, you can easily hear a full-blown knocking and pinging with the help of a knock sensor.

How do you install a knock sensor?

Issues with your knock sensor not be ignored because continuous pre-ignition can bow holes on the Piston and eventually destroy the pistons and the entire engine. If you have done any minor or major work on your car successfully, you can install a knock sensor by just

  • locating the knocking sensor
  • Unbolting the fastening bolt with common mechanic tools
  • Unplugging the connecting wires
  • Reinstalling the new one and tightening the connecting wires.

If you can’t locate the knock sensor on your car, you might want to contact a professional mechanic. Some sensors require taking off many other components before you can get to them.

How much does it cost to replace a knock sensor?

The cost of replacing a knock solely depends on few things. Your car makes, model, year, and the dealership you want to take your vehicle to. However, the average cost of replacing your knock sensor should be between $130 to $700. The range is this big because some cars utilize one knock sensor, some two sensors, and few other four sensors. The average price of a knock sensor $40 – $50, while the service fees range from $90 – $300.

What Are the Symptoms of a Bad Knock Sensor? YouTube

Final Thought.

Getting to this point means that you must have known what causes a knock sensor to go bad and the symptoms of a bad knock sensor. So, Once you notice any of these faults, not just one of these symptoms, but two or three at once, you should seek professional advice to avoid unnecessary damages to your entire engine.

Osuagwu Solomon

Osuagwu Solomon is a seasoned automotive technician for the past 9 years, and a technical writer. He loves writing about auto professional repair guides, DIY repair guides, and buyer’s guide. After spending six years in the automotive workshop, he decided to impact his knowledge to people aside his domain, and he has achieved this by centering his Automotive writing skills on REPAIRS.

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