What is Spark Plug Non Fouler, And How Do You Install It?

Car owners and motorists face endless issues with their spark plugs. However, we can curb spark plug problems and ensure the engine runs fine by utilizing a spark plug non-fouler. Using a non-spark plug fouler will protect your engine from misfiring, poor acceleration, reduced fuel economy, and whatnot.

In this article, I’ll explain what a spark plug non-fouler is, what it does, the types of spark plug fouling, and the best spark plug non-foulers. You’ll also learn how to choose the right spark plug fouler and how to install it. Sit back and relax while I uncover all you need to know.

What is Spark Plug Non Fouler

What is a spark plug non-fouler?

A spark plug non-fouler, also known as a spark plug anti-fouler, is a metallic car component that helps to prevent a spark plug from fouling and damage. Does spark plug non-foulers work, anyway? Yes, they help boost engine performance, especially when there is an oil leak or rich fuel mixture issue. We typically screw spark plugs into the spark plug non-foulers. This makes the non-foulers serve as a sleeve to the spark plugs.

The non-foulers have a small hole that allows the plugs to ignite the air-fuel mixture in the combustion chamber to power the engine while preventing oil, fuel, or other contaminants from fouling the plugs. Non-foulers are short-lived or temporary fixes for burning oil and constant fouling of spark plugs.

The non-foulers are forged from quality steel that resists corrosion, which makes them suitable for any head cylinder.

What does a spark plug non-fouler do?

As explained earlier, spark plug non fouler 42009 and other non-foulers prevent plugs from fouling and damaging. The purpose of spark plug non foulers is to serve as a sleeve or coating that prevents plugs from fouling or damaging due to burning oil.

We also have spark plug non foulers for oxygen sensors. These type of non fouler serves as a sleeve, coating, or adapter to the O2 sensor. We screw in the O2 sensor into the fouler and screw the other end of the fouler into the exhaust pipe. These foulers clear P0420 error codes and check engine lights caused by low catalyst efficiency warning.

What are the three types of spark plug fouling?

The three types of spark plug fouling are carbon, ash, and oil fouling. Each plug fouling connotes a different issue that needs to be addressed on time.

Carbon fouling

Carbon fouling happens when black, dry soot covers the spark plug tips. Carbon fouling usually results from too rich air-fuel mixture, short tip plugs, weak ignition, and improper heat range.

One of the most common symptoms of carbon fouling is engine misfires.

Though, several other factors can cause engine misfire. Therefore, you don’t have to accuse the spark plugs until you remove and check the tips and threads.

Oil fouling

Another notable type of spark plug fouling is oil fouling. This occurs when engine oil enters the combustion chamber through worn pistons or defective valve oil guides. It can also happen due to a failed gasket and worn or bristled spark plug tube seals. If oil deposits cover the spark plug gap, it will prevent the plug from arcing across the gap.

Ash fouling

Ash deposit is similar to carbon fouling. The difference is that the ash deposit is dry, white, and sandy in texture, whereas carbon fouling is black and dry.

Ash deposit or fouling happens when there’s too much ash buildup on the plugs. This usually occurs due to defective PCV valves, overdue oil changes, and low-quality engine oil.

Best Spark Plug Non-Fouler for Cars, Trucks & SUVs

While several spark plug non foulers are in the market, you need to understand some are not as effective as others. Don’t worry; I don’t want you to go through the hassle of finding a reliable spark plug non fouler. Here are the best non foulers for cars, trucks, & SUVs.

Dorman 42004 Spark Plug Non-Fouler

Dorman offers several premium spark plug non fouler for different cars, trucks, SUVs, and other applications. The Dorman 42004 non fouler is constructed with quality steel to prevent corrosion and enhance engine performance. It also preserves spark plug life and is a reliable replacement for any failed non foulers of the same size.


  • Easy installation
  • Trustworthy quality
  • Durable construction
  • Ideal solution to prevent plug fouling.

Dorman – HELP 18mm Spark Plug Non Foulers 2 Pack 42009

Dorman spark plug non fouler 42009 is graced with Dorman’s high-end reputation. It is one of the best non foulers produced by Dorman. And it is engineered for reliable performance and long durability.


  • Easy to install
  • Preserves spark plug lifespan
  • Made from quality material
  • Reliable performance for preventing plug damage and fouling.

2Pcs O2 Sensor Spacer, M18*1.5 Spark Plug Non Fouler

This spark plug non fouler is designed explicitly for O2 sensors. The M18 1.5 spark plug non fouler is threaded into the catalytic converter while the O2 sensor threads into it. It tricks the O2 sensor into appearing perfectly functional.

It also resolves a P0420 error code, which indicates a low catalyst efficiency warning system. However, this is illegal in the United States and may be illegal in other countries because it is rigging.


  • It clears error code P0420 and check engine light
  • Easy straight bolt-on installation
  • Ensures maximum strength and durability
  • Universal fitment.

2Pcs Universal O2 Oxygen Sensor Spacer Adapter

This spark plug non fouler for catalytic converter is made of high-quality material to prevent rust on the O2 sensor. It eliminates check engine lights caused by a P0420 error code and also erases the fault code. Plus, it has universal fitment for most vehicles.


  • Universal fitment
  • Eliminates error code P0420
  • Clears check engine light
  • Reliable and lasts strong.

Universal O2 Sensor Spacer Adapter Isolator Extender Straight CEL Fix Kit

You should try this reliable spark plug non fouler for O2 sensors. The manufacturers design it with high-quality material compatible with almost all vehicles.


  • Easy to install
  • Universal fitment
  • Clears check engine light caused by error code P0420
  • Clears trouble code P0420.

How to install spark plug non fouler

Installing a spark plug non fouler may be an ideal thing to do if done correctly. Here are the step-by-step procedures on how to install spark plug non fouler. But first, you must have all the necessary tools at your disposal.

Fit the sensors

Cars typically have one or two rooms for spark plugs anti-fouler. If you choose to install it in multiple plugs, you may have to do drilling work. Ensure you have at least a spark plug non fouler 18mm before starting the installation.

Disconnect the negative battery terminal to reset the powertrain control module (PCM). Locate the center of one non-fouler and drill it down to half. This will create enough space for the sensor to fit in properly.

Reinstall and reconnect

Take the sensor, apply some anti-grab, and reinstall it following reverse method. Reconnect the negative battery cable you removed earlier. You have successfully installed a spark plug non fouler.

How to choose the right spark plug non fouler

You have to consider several factors when choosing the proper spark plug non fouler for your specific car model. These include the reach of the spark plugs and the thread size. Here are what to consider to make the right non fouler buying decision.

  • Browse the internet and check your car manual for the correct plug size and reach. You’ll likely get this information under the engine specification.
  • Measure the reach of your existing spark plugs and the thread size using a spark plug gap gauge and a thread pitch gauge.
  • Choose the spark plug non fouler that matches the reach of your plugs. There are typically 14 and 18mm.
  • Ensure you have a compatible non fouler. Producers specifically designed this for copper or platinum plugs.
  • Get the exact number you want. There’s one non fouler for each plug.

Frequently Asked Questions – FAQs

Q: Do spark plug non-foulers work on O2 sensors?

Yes, spark plug non foulers work 100% on O2 sensors for reducing emission issues and clearing fault codes on the car computer. One of the best spark plug non foulers for O2 sensors is the Dorman spark plug non foulers 42002. It fits several car makes and models like Ford F150, Dodge Charger, Hyundai Entourage, Subaru Foresters, etc.

Q: Do spark plug non-foulers really work?

Spark plug non foulers do not only prevent spark plug damage but also prevent fouling. If your engine runs rich or has oil issues, installing a spark plug non foulers will fix the problem, at least for the short term. It also improves overall engine performance in the case of rich engine running or burning oil.

Q: What is the best spark plug to resist fouling?

Platinum spark plugs are rated high because of their longevity. It also runs hotter than conventional spark plugs, making it better for burning off carbon deposits and resisting fouling. So, if you are looking for the best spark plugs to resist fouling, get a platinum spark plug.

Q: Will a colder spark plug stop fouling?

Electrical performance is one of the things to consider when choosing the right replacement plugs for your vehicle. Manufacturers specifically design colder spark plugs to prevent pre-ignition, while hotter plugs avoid fouling. So, if you are looking for spark plugs to prevent fouling, get hotter spark plugs.

Q: Why are my spark plugs fouling so fast?

Several factors can cause spark plugs to keep fouling so fast. Some factors occur in rare cases, while others are common. The most prevalent reasons spark plugs keep fouling are dirty air filters, wrong plug gaps, dirty fuel injectors, excessive stop-and-go driving, idling your car for too long, and a rich fuel-air mixture.

Final words

If you have been reading to this point, you know what a spark plug non-fouler is and what it does. If your spark plugs keep fouling due to burning oil or any other thing, install a spark plug anti-fouler to protect the plugs from fouling and damage. It’ll also protect the engine from poor performance.



While growing up, I knew I had a thing for car repairs though my parents never wanted me to learn mechanics. I always visit a mechanic garage in my small neighborhood after school. As I grew older, at age 16, I got addicted to anything automotive. My parents had to enroll me in that mechanic garage since giving up was never an option for me. As a dedicated mechanic who got into the industry from an early age, I'm graced with an addiction to diagnosing and rectifying automotive problems with ease.

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