Can I Drive with a Bad Knock Sensor?

The engine of your car is constructed with lots of different parts that work together to allow the engine to operate as it should.

The knock sensor (colloquially also called the nox sensor) is one of these essential components. But what exactly is a knock sensor?

What are the signs that it has gone bad? And most importantly, can you drive with a bad knock sensor? If yes, how long can you drive with a bad knock sensor?

If you want the answers to these questions, read on to find out.

What does a knock sensor do?

The knock sensor is an essential component of your car’s engine. When you press down hard on the accelerator you may hear a small noise from the pedal and the engine, this is an engine knock. If this happens, the knock sensor will be triggered.

It is the knock sensor’s job to pick up any sounds or vibrations emanating from the engine block. If the knock sensor picks up a vibration or a sound it will change this into an electronic signal which is transmitted to the engine control unit.

The car’s computer can then receive this information and judge whether any changes to the car’s ignition are needed.

In most vehicles, the knock sensor will be located directly next to the engine block. This allows the knock sensor to easily pick up any noise or vibrations from the engine upon acceleration.

In some modern cars, if the knock sensor picks up any noises or vibrations this could cause a light to appear on the dashboard. This usually appears as the check engine light. Alternatively, the engine may decide to shut itself down if the knock is particularly bad.

It is the knock sensor’s job to inform the car’s computer of anything untoward, so what happens when something happens to the knock sensor?

Also read: Have you ever wondered how much time does it take to build a car?

Signs of a bad knock sensor

Before we dive into the issues that a bad knock sensor can cause, let’s look at the signs that you should watch out for that could be warning you of a bad knock sensor.

It is the knock sensor’s job to identify engine knock in your car and its job to prevent this knock from causing any further damage to the vehicle. When a fault occurs in the knock sensor, the symptoms of this fault will be felt throughout the car.

There are some common symptoms of a faulty knock sensor that you should watch out for, including:

  • The engine warning light appearing on the dash
  • Reduced engine power when you are driving
  • A noticeable increase in fuel consumption
  • An error code is stored on your car’s computer
  • Loud noises while driving

If you notice any of these symptoms you should take your vehicle to the garage and have it looked at.

Especially if you are experiencing more than one of these symptoms simultaneously.

Causes of a bad knock sensor

Now that we’ve established the symptoms of a bad knock sensor, and that you know exactly what to look out for, we must understand how these issues are caused.

The knock sensor is, as its name suggests, a sensor. This means issues within the knock sensor can be easily caused by issues emanating from other areas of the vehicle.

One common cause of a bad knock sensor is down to timing.

Timing is essential to the start-up and operation of your vehicle’s engine, so if there is a delay in the spark igniting and starting the engine this could cause damage to the knock sensor. Especially if the timing is consistently off.

Another common cause of damage to the knock sensor is dirt. There are a lot of fumes that pass throughout the car’s engine and over time these can build up and cause issues for the knock sensor.

Dirt, grime, and lots of other contaminants can easily enter the cylinder and overtime develop into dirt deposits. If the issue is down to dirt, this can be fixed if caught early.

One more, fairly common cause of issues with the knock sensor is down to the spark plugs. Spark plugs can cause a variety of different issues within your car’s engine.

It could be that you have the wrong type of spark plug installed, that the spark plug has been installed incorrectly or that dirt deposits have built up around the spark plugs. All of these issues could lead to faults with the knock sensor.

Can I drive with a bad knock sensor?

Moving onto the all-important question, ‘can you drive with a bad knock sensor?

Like the answer to many questions in life, the answer to this one is not straightforward.

You can drive with a bad knock sensor. But you might want to do something about it sooner than later. Driving with a bad knock sensor is not the best idea.

Once the function of the knock sensor has been damaged, you will start to experience all of the symptoms that we’ve already covered. From reduced performance to increased fuel usage, it is likely that these symptoms will put you off using the car until the sensor has been fixed.

The knock sensor is an essential component that ensures your car is running smoothly, and more importantly safely. So when it is faulty, the knock sensor will be unable to complete this job.

Due to this, it is advised that you take the car to the garage as soon as you experience the above mentioned issues with your car. If this is not possible you should try and reduce your driving as much as possible until you can get the car checked.

How long can you drive with a bad knock sensor?

While it is ok to drive with a bad knock sensor for some time, prolonged use of a car with a faulty knock sensor is not ideal.

Can a bad knock sensor damage the engine?

Apart from increased fuel consumption and noise while driving, a faulty knock sensor can cause a lot of damage to the car’s engine. And replacing a knock sensor is not that pricey, an engine rebuild definitely is. It is not exactly safe for your car’s engine if you are driving around with a damaged knock sensor.

So if you suspect any such issues that we talked about above, the best thing to do is take it to the garage and get your car checked. A qualified mechanic should be able to replace the faulty knock sensor and your car should be ready to go in a couple of hours.

Summary – Driving a car with a damaged knock sensor

In short, the answer is yes, you can drive a car that has a faulty knock sensor.

That being said, you may not want to. The prolonged driving of a car that has a bad knock sensor can cause a lot of damage to the engine.

It is much cheaper to get the knock sensor replaced than the engine so you should try and limit driving as much as possible if you suspect your car has a faulty knock sensor.

Photo of author

Sean Mendez

Hi, I am Sean, a self-confessed petrolhead. I live in Boise, Idaho with a busy family of four and our energetic Labrador retriever. Thank you for visiting my website. You can find my email on the contact page.

Leave a Comment