What Spark Plugs Fit My Car? – Figure out from This In-depth Guide

A vehicle’s engine can only start with a functioning ignition system. However, this ignition system consists of several components, one of which is the spark plug. The spark plugs are responsible for igniting the air-fuel mixture in the combustion chamber to start the engine.

However, because they are constantly exposed to heat, they wear out. In other cases, they wear out due to age. But whatever the reason for wearing out is, they must be replaced. But the thing is, these replacement plugs come in varying types and sizes, not to fit all.  Hence, this has prompted people to ask, what spark plugs fit my car?

do spark plugs fit all cars

How to know which spark plugs fit my car?

Spark plugs come in different types, size gaps, and lengths, so it’s proper that you select only the type that meets your engine’s specifications. So, how do I know which spark plugs my car needs? There are a few places you can get this information from; let’s explore them.

Your vehicle’s owner’s Manual

All vehicles come from the factory fitted with OEM spark plugs. These OEM plugs are built to withstand your vehicle’s performance and fit the compartment created for it and, therefore, the best fit for your car. So to get information about your manufacturer-recommended spark plugs, check your vehicle’s handbook.

They not only detail the type and size recommended but also include their parts numbers. Note that your handbook will only state the OEM spark plug and not an upgraded version. For example, while the manual will only state the factory CR8E, you could buy an upgraded version, such as CR8EIX, from NGK.

Use your supplier’s guide.

Many auto shops have a spark plug chart detailing spark plugs for different vehicle brands and models. Use your vehicle make and model to find the best fit for your car. Even if the recommended plugs are no longer in production, their spark plug cross-reference charts can help find an alternative.

Simple online tools

Technological sophistication has made life even easier. There are simple online tools like the spark plug finder used to find the best spark plug for your car. By entering your vehicle’s registration number using the drop-down menus, you should see a list of suitable spark plugs.

In other cases, these online spark plug finders will require you to select other information from a drop-down menu before showing you options. This information may include your vehicle make, model, year, engine size, etc. These online tools are also helpful if the manufacturer-recommended spark plugs or its upgrade is no longer in production.

In this case, spark plug cross reference comes into play. Cross-referencing spark plugs means looking for plugs that can fit in when the recommended plugs are unavailable. Online cross-referencing tools for spark plugs only need your manufacturer name and the part number of the old plug to find another suitable match other than what was recommended.

Note that if your vehicle is performance modified, the spark plug options suggested by these online tools may not fit your vehicle. This is true because the vehicle setting has been tampered and these tools will only list options that tally with the vehicle before modification. In this case, you should talk to an expert to find the best fit for your car.

what spark plug for my car

Frequently Asked Questions-FAQs

Q: Do all spark plugs fit all cars?

Do spark plugs fit all cars? No, all spark plugs will not fit every vehicle. Spark plugs come in varying lengths, gap sizes, and types, each built for specific vehicles with such lengths, gap sizes, and performance. So before opting for one, ensure the plug tallies with the engine’s specs. 

Buying the wrong type or size spark plugs will not only cause performance issues but also reduce the lifespan of the plugs. The quicker they wear out, the more money you spend. For those wondering, are spark plugs universal? Now you know they are not a one-size-fits-all things. Specific plugs are built for particular cars.

Q: What happens if you put the wrong spark plug in your car?

Putting the wrong spark plugs in your car can cause performance issues and incur avoidable expenses. Spark plugs come in different types and sizes, which of course, should be fitted to specific vehicles. Generally, the wrong-sized spark plugs won’t even enter into the plug’s thread. However, it is possible. So let’s say they enter into the thread. Here’s what will happen.

If it’s too long, it can start hitting the cylinder and damage the pistons. Remember, papers are not used to repair or purchase new pistons. In case they are too short, they will find it difficult to ignite, causing engine misfiring. With the engine misfiring, vehicle acceleration may be tampered to decrease its fuel efficiency.

Improper ignition of the air-fuel mixture also results in incomplete combustion, hindering vehicle power output. Resulting in hard starts, rough idling, smoking engine, and sometimes vehicles are unable to start. If you use a performance plug in a regular car, you may also experience performance issues.

Q: Can you put any spark plug in any car?

No, you can’t. When replacing spark plugs, understand that specific engines need specific spark plugs. While your replacement plugs must not be the same as the OEM brands, they must be of the same type. That is, they must have the same dimension, design, and heat range.

For example, iridium plugs are strong and therefore offer outstanding performance. But putting an iridium plug-in engine built to use copper plugs is wrong and can cause performance issues. If I can’t use any plug, what spark plugs for my car are the best? Choose the ones that match your OEM plugs spec; this should be stated in your owner’s manual. 

It could be an upgraded version, but it should be of the same type recommended by your vehicle manufacturer. An excellent example of upgraded plugs is those from NGK. But then, not all plugs from that brand will fit your car. So you may ask, what ngk spark plugs fit my car? Use the online NGK part finder and, if necessary, their cross-reference chart.

Q: Does spark plug size matter?

Spark plugs come in different sizes, with each size built for specific vehicles. So yes, spark plug size matters. If you buy the wrong sizes, they won’t even fit into the thread. And even if they enter the thread, they will cause performance issues and incur extra expenses. How?

If they are too long, they may rub against the cylinder, invariably damaging the pistons and, eventually, the engine. If they are too short, they won’t be able to ignite the air-fuel mixture properly. This results in misfiring, which hampers acceleration and reduces fuel economy.

Inability to ignite also results in incomplete combustion causing your vehicle to lose power and even cause a no-start situation. So for those asking, do spark plugs affect car performance? Yes, it does. Using worn or wrong spark plugs will cause performance issues.

Q: How do I know my spark plug size?

Are all spark plugs the same size? No, spark plugs come in different sizes, and not all will fit your car. So you may ask, how do I know my spark plug size? Your spark plug thread size determines which spark plug size you buy. The spark plug thread size fastens the spark plugs into the cylinder head.

The most common spark plug thread size on many automobiles is 14mm, 12mm, and 10mm. Generally, you may see the sizes written like this —14×1. The first number (14) represents the diameter, while the second number (1) is the pitch which indicates the distance between the threads in millimeters.

To get what spark plug thread size your vehicle uses, check your owner’s manual. If you don’t have your manual, you will need to measure your old plugs yourself. In summary, if you know the spark plug thread size, you already know which size spark plug your car needs.

Q: Does a spark plug need to be exact?

Spark plugs come with various gap sizes. So does it need to be exact? Yes, but while the spark plug gap should tally with the gap it should be fitted in your vehicle, little difference won’t hurt the engine. In many cases, OEM spark plugs are always exact, so they won’t need adjustment. However, you may not always get spark plugs with the recommended gap.

In that case, you will need to adjust the gap to fit into your vehicle. However, gapping can be challenging, especially with iridium and platinum spark plugs. If the gapping is done incorrectly (too far from the ideal gap size), you may start experiencing engine issues.

If the gap is too large, you will experience engine misfires since enough voltage doesn’t enter. Suppose the gap is too narrow; it will result in incomplete combustion, leading to power loss due to a weak spark. You may also notice the plugs wearing out faster, fouling, and decrease in fuel mileage. So it’s either you buy one with the recommended gap, or you are good at gapping.

Q: Should you reset your car after changing spark plugs?

Resetting the car after changing the spark plugs is not necessary. If your vehicle doesn’t start after installing new spark plugs, you probably didn’t do the installation correctly. In this case, you will need to reinstall the plugs in the correct order. If you don’t know how to fit spark plugs correctly, visit an expert.

However, in cases where the vehicle runs well after changing the plugs, resetting your car may not also be a bad idea. You could reset it by removing the clock fuse or disconnecting the battery.  But be sure you aren’t due for a vehicle inspection the following week. The reason is at that time, the vehicle may not have relearned the operating parameters, hence won’t be ready for a scan.

Q: Will I notice a difference after changing spark plugs?

If the old spark plugs were probably faulty and were responsible for the engine issues you were having, you should notice a difference after changing the plugs. If, however, you change old but still serviceable plugs to new ones, you may not really notice a huge difference. This is true because these plugs, while old, are still active.

Note that manufacturers gave a recommended time to change spark plugs. So change them accordingly before they start malfunctioning. While doing this, ensure you use only plugs recommended for your engine. Plugs from different brands are acceptable so long they tally with the spec recommended by your manufacturer.

Q: Can a spark plug destroy an engine?

Spark plugs can destroy an engine in several ways. Faulty spark plugs left for too long could destroy the piston rings and crank bearings. Suppose you replace using the wrong size plugs; you could also cause piston damage and misfiring issues.

But one of the cases that can lead to permanent engine damage is using plugs with the wrong heat range.

Generally, spark plugs come in various heat ranges. Suppose the plug’s heat range is higher than what the vehicle engine needs; overheating may occur in the combustion chamber. Too much heat in the combustion may invariably lead to an engine knock. So ensure you stay within your plug’s specified heat range.

Q: Does upgrading spark plugs make car faster?

Upgrading spark plugs don’t make a car faster; upgraded plugs are only durable. Generally, there are three types of spark plugs —copper, iridium, and platinum. But using the least of them—copper will even make a car faster. How? Of the three types, copper is the best conductor and can transmit more power from the ignition system.

Copper plugs, due to their softer metal, generate a stronger spark, which quickly ignites the air-fuel mixture, thereby producing more power to make your car after and more fuel efficient. The only difference between copper and the other spark plug type is copper plugs have shorter lifespans.

The others, however, are stronger and more durable and could last up to 100k miles. In a nutshell, upgrading spark plugs won’t make your car faster, but it can make your plugs last longer due to the stronger materials used in manufacturing those plugs. If you need to drive faster, continue using your standard copper plug.

Q: How do you match spark plug?

Matching spark plugs entails choosing those that conform to the manufacturer’s standard. This includes the hex size, diameter, thread pitch, and heat range. You must also consider your engine design.

While iridium and platinum will last longer, copper spark plugs are good conductors. So, how do I know the best spark plugs for my car? Check what your manufacturer recommended in your owner’s manual and match those specs with the upgraded aftermarket plugs if you can’t get OEM plugs.

Final Words

This article has answered what spark plugs fit my car and the queries that can complement your knowledge on this topic. The best fit is that came stock with your vehicle, whose information you could get from your owner’s manual. Online spark plug finders like the bosch spark plug finder can also help in finding the best fit for your specific vehicle. All you need is your vehicle registration number, that is, using the spark plug finder by reg.

In other cases, you may need other vehicle details like the make, model, year, engine number, or the number of cylinders. While you may not always get OEM plugs, let the upgraded version or brand be the same type as your manufacturer recommends. Using the wrong spark plugs not only cause performance issues but can incur unnecessary expenses.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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