Home Diagnosis and TroubleshootingMaintenance and Servicing How Long Do Spark Plugs Last – Are They That Durable?

How Long Do Spark Plugs Last – Are They That Durable?

by Jordan Harris
How Long Do Spark Plugs Last

Are you thinking of replacing the spark plugs on your car and you are asking yourself how long do spark plugs last? If this is the case, we are going to answer this question for you and we will elaborate on the bad spark plug symptoms that you might as well encounter during your ownership.

Doing preventive maintenance on your car is key if you don’t want to be left stranded one day. Because if you push every component to the max, being left on the side of the road and unable to start the car is unavoidable. And you don’t want to deal with all this anger and frustration, to be honest. You will have your day ruined as well you are going to pay a big towing fee to take your car to a mechanic.

Replacing all the components that suffer wear and tear on a daily basis when their time has come is key to avoiding these situations. But what are these components? The main components that suffer wear and tear are the spark plugs, battery, cables if you are running a carburetted car. These components are essential for starting the vehicle and without them, you will not be able to start the vehicle.

That’s why in this article, we are going to learn everything when it comes to spark plus and the symptoms of bad spark plugs. Then we will take a look at how long do spark plugs last and how to extend their lifespan. We will also discuss how to replace them and the cost to replace them. So, let’s get started.

What Are Spark Plugs?

Before we dive deeper into the topic of how long do spark plugs last and symptoms of bad spark plugs, let’s first cover some of the basics when it comes to spark plugs. This will be essential for those that are not into mechanics and want to learn more about how they work in reality and what is their task.

Spark plugs are special devices that are mounted to the engine and their goal is to deliver the electric current also known as spark accordingly to start up the engine. They are a basic electrode design that hasn’t changed since their first introduction onto the market. So, why is this the case? This is the case because they simply work. And what is not broken you should not fix it.

Spark plugs are located on top of the engine between the intake and exhaust valves. But how do they work in reality? It is really simple to explain.

Spark plugs have a special task to release electric current to ignite the fuel whenever there is a need to do so. And here the timing comes into place. In older vehicles, the work of the spark plugs is regulated by the distributor which tells the spark plugs when to release the spark. But in modern vehicles, this process is regulated by the car computer.

But like with every other component, spark plugs also have a service lifespan. And sometimes they can be even affected by other problems in the engine like oil burning issues, lean or rich air to fuel mixture. All these things can damage the electrode of the spark plug and make it unusable. But how long do spark plugs last? More on that in a bit.

Symptoms Of Bad Spark Plugs

Before we cover how long do spark plugs last, let’s first discuss the symptoms of bad spark plugs. Knowing the symptoms is going to help you out with telling if your spark plugs are due to be replaced and whether you should replace them or not.

1. Rough Idle And Engine Misfires

One of the first symptoms that you will notice when the spark plugs are failing is the rough idle and engine misfires. The engine will simply not work at stable RPM and the numbers will rise and drop.

Basically, the engine will have a hard time operating properly. This is because of the misfires that are happening inside the combustion chamber. The misfires can be heard like small taps in the cylinder head. Or if you place your hand at the exhaust, you will notice how the smoke doesn’t exit evenly and there are pops here and there.

How Long Do Spark Plugs Last

This indicates a problem with the ignition. The most probable reasons are the spark plugs or coils. If you are running an older model, then there is a high chance that the distributor is also bad.

Whenever you experience these symptoms, it is key to look online for how long do spark plugs last and diagnose the problem. Later on, in this article, we are going to explain to you how you can diagnose this issue quickly and effectively at home using only one deep socket wrench.

Anyway, when you notice a symptom like this. It is key not to continue driving like this because you never know when your car will fail completely and will not even like to start and that we are going to cover in the following chapter where we will elaborate this symptom in great detail.

2. Car Doesn’t Want To Start

One of the worst symptoms that you can experience is the problem when the car doesn’t want to start at all. This can be a really frustrating thing to deal with.

Imagine that it’s freezing cold in the morning and you have to go to work. The car simply doesn’t want to start at all. You keep on cranking the engine but it just doesn’t want to start.

This is frankly, the worst. You don’t want to end up in this situation because not everybody has understanding for you. Imagine that you are late for work and you show up 2 hours later. Your boss will be furious at you probably and you don’t want that. You can get a deduction from your salary as well to work some extra hours after your work time has ended. Bad situation.

That’s why you need to learn how long do spark plugs last and replace them on time before they fail and cause you these issues. For sure before the car fails completely there will be some signs that will tell you that there is something wrong. And you should not ignore them at all.

Soon after you notice that the car cranks too long, there is a reason for this and when you notice this you need to invest your time in diagnosing this issue. How you can diagnose this problem we are going to cover in one of the following chapters where we will elaborate this process in-depth and we will learn how to spot if your spark plug has failed.

Now let’s move on to the next symptom that is also quite frequent when you are having a bad spark plug issue on your car.

3. Check Engine Light

The check engine light will also probably be there to remind you that you are having an issue. But unfortunately, when you are having a check engine light you don’t know what kind of an issue you are having with your car.

So, if you have misfires and rough idle, there is a high chance that the check engine light will appear and ruin your day. In this situation, it is up to you to take things further and diagnose the problem.

For this purpose, you will need an OBD2 diagnostics tool. The diagnostics tool is connected to the OBD2 port of the vehicle. Every modern car has one of these ports that allow you to make some quick diagnosing performed. Overall, an excellent tool that will make your life easier and you will be able to solve your problems much quicker than with experimenting.

How Long Do Spark Plugs Last

You just plug in your tool in the port and let it scan for codes. Then look for the codes online and learn more about them.

Since the spark plugs are not connected to the computer, the tool will not tell you that the spark plug went bad but it will tell you that there is a misfire on that specific cylinder. And will be up to you to take things further and learn more about this problem.

But more on diagnosing we are going to cover later. Let’s first discuss the rest of the symptoms that can happen when there is a bad spark plug.

4. Car Doesn’t Want To Accelerate

And the last symptom of bad spark plugs is the lack of response from the vehicle. The car would simply do not want to accelerate that well when you are having bad spark plugs. But why is this the case?

This is the case because, for your engine to work, there is the need for some explosions to happen into the cylinder. So, if explosions do not happen at all in some of the cylinders, your car will simply work on 1 or a few cylinders less. This means that it will be significantly down on power and you will have a hard time accelerating.

Acceleration can be crucial in some situations. For example, when you are overtaking someone on the road. You could get yourself in danger if the car simply doesn’t have the power to accelerate appropriately.

Another thing is driving uphill. The car will not like this when you will try to take it uphill. This can also be misdiagnosed with a bad clutch if you have a manual gearbox. That’s it is a good idea to take note of this.

Whenever you notice how the car doesn’t want to accelerate. It is a key thing to look online for how long do spark plugs last and learn more about the diagnosing of this problem quickly and effectively. And that is something that we are going to cover in the following chapter.

How To Diagnose A Bad Spark Plug?

Diagnosing a bad spark plug can be pretty tricky to do since you have to get your hands dirty. On carbureted engines, this is fairly simple. You just remove the spark plug from the engine and mount it on the cable. Give the engine a good crank, if it makes a spark, then the spark plug is good. If it doesn’t then you know that it has some problems.

In modern engines, things are a bit different and you need to learn how to read the spark plugs by their color. But first, you need to diagnose which cylinder has a bad spark plug.

How Long Do Spark Plugs Last

As we mentioned above, diagnosing is done by getting yourself an OBD2 scanner and scanning the car for possible errors. If you have a code for a particular cylinder. The next thing you will need to do is to get a long socket wrench and remove the spark plug from its position.

Once removed, take a good peek at the condition of the spark plug and see any discoloration or damage done to the electrode. If the electrode is damaged and almost gone, it means that the spark plug is bad and has to be replaced.

Also, if the electrode is a bridge between the electrode it means that this electrode isn’t firing. There should be a clear space between the electrode and its top part.

Spark plugs can also wear different colors, if they are all black and oily it means that the engine is burning oil. If the spark plug is soaked in gas and it reeks on gas then the spark plug is bad and the engine is running too rich. If there are ash deposits or damage to the electrode it means that it is running too lean.

How Long Do Spark Plugs Last?

Now we came to the important bit and that is to see how long do the spark plugs last. The answer to this question is that it depends. A good set of spark plugs should easily last for about 60,000 miles. The spark plugs are not components that are often replaced.

But for a good measure, it is useful to replace them at 30,000+ miles. Don’t run your car on the same set of spark plugs for too long. Even if they look good as new and there isn’t much to them because you never know when some of them could fail and ruin your day. Replacing them is not expensive and that’s why we encourage you to replace them.

If you do this work by yourself it will not cost you more than $60 if you have a straight-4 engine. If you have a V8 you will have to pay a bit more, but nothing significant.

Also, there are a ton of other factors that decide the fate of your spark plugs as well. Spark plugs most often fail by other problems of the engine than on their own. They are sensitive to fuel-related issues and other types of mechanical problems like valve issues, oil consumption, and uneven air to fuel mixture. All these things can attribute to the premature failure of the spark plugs.

And in the following chapter, we are going to cover precisely that where we will learn what issues can cause your spark plugs to fail and how to extend their lifespan.

How To Make the Spark Plugs Lifespan Longer

We discussed how long do spark plugs last, now let’s cover something very useful for you as an owner and that is how to extend the spark plug life.

Spark plugs tend to fail soon on some vehicles because of several different factors. A set of spark plugs last for 60,000 miles only if some conditions are met. If not the spark plugs fail sooner than the 60,000 mark.

Factors like oil burning, leaky valves, and bad fuel to air mixture are affecting the spark plugs greatly and they can reduce their life significantly.

So, if you have fouled spark plugs on your car and your spark plugs are often known to foul (and if you’ve yet to understand how to clean a spark plug and how to clean spark plugs). You need to take some action. Depending on the reason, you have to perform some repairs on your engine.

For example, if there are leaky valves, you have to do a valve job on your car. This might come expensive but it is better to fix it if you don’t want to replace your spark plugs all the time.

Another reason is the wrong fuel to air mixture caused by bad mass airflow sensors or bad O2 sensors. It doesn’t matter which is the cause of the problem, it is important for you that you address the issue sooner than later.

The spark plugs should always look clean with a slight discoloration from the explosions that they are making. And they should not look black with oil and carbon deposits or damaged by lean air to fuel mixture.

How To Replace The Spark Plugs DIY?

We have answered how long do spark plugs last. Now let’s see how they are replaced. Replacing the spark plugs is not a difficult task to perform and anyone could do it. The important thing you will need to have is a long socket wrench that will fit the spark plug.

But you shouldn’t just jump right into it and do the job. First, watch some YouTube videos and learn how this process is done to your car in order not to do any possible damage to some of the components. So, which are the steps involved? Let’s find out.

Step 1

Step 1 will involve preparing the car for removing the spark plugs. This involves removing the positive terminal from the battery as well as removing the spark plug covers that are located on top of the engine head.

Step 2

After uncovering the engine head. The next step would be removing the coils. The coils are held by one or two screws and they will pop off easily.

Step 3

The next thing to remove is the spark plugs. Get your long socket wrench and place it inside and remove the spark plugs one by one. After removal, inspect them for issues and see their condition.

Then place the new spark plugs in and torque them to spec. Also, bolt-on and connect the coils accordingly. The last step is to connect the positive terminal and start the car. It’s that simple to do. After this, you are good to go.

Cost To Replace The Spark Plugs

The cost to replace the spark plus is really cheap because they last for a long time and you can do this work all by yourself.

A single spark plug is as low as $15 apiece. Imagine that you have 4 spark plugs, you will only have to pay $60 in total. Or if you have a V8, you will spend $120. What is worse is that some of the engines are using twin sparks. For example, if you use a HEMI V8, then it is highly likely that you are running twin spark.

So, replacing all these spark plugs on this engine will cost you $240. Which is kinda a lot of money, to be honest.

The labor is also cheap for replacing spark plugs. It will not cost you more than $150 to $250 to do this work. But some shops tend to demand more and you should be aware if you don’t want to get ripped off.

Should You Go For More Expensive Spark Plugs?

We learned how long do spark plugs last. Now let’s see if you should go for more expensive options out there. The answer to this is no. If you are running a regular car that is not performance-oriented, you should not spend a ton of money. To get a set of really expensive spark plugs because you will not see a huge difference.

Facts about Spark Plugs and Their Importance in a Vehicle:

  1. A failing spark plug can trigger the check engine light, which could lead to potentially catastrophic misfires.
  2. Misfiring spark plugs can cause rough idling, uneven power, and an increase in exhaust emissions.
  3. Keeping spark plugs in good working order can help save you from costly repairs and prevent undue stress on your car’s catalytic converter.
  4. A flashing engine light could mean a spark plug failure, but it’s important to note that it could be potentially caused by a number of things.
  5. Old, worn-out spark plugs can cause your car to stall when starting and have trouble accelerating.
  6. Worn spark plugs can reduce your vehicle’s fuel efficiency by up to 30%.
  7. Keeping your car tuned up can work wonders for your fuel efficiency and improve gas mileage by an average of 4%.
  8. If you hear rattling, pinging, or knock-like noises coming from your engine, it could be a sign of worn spark plugs.
  9. It’s always best to follow the manufacturer’s suggested maintenance schedule when it comes to replacing spark plugs.
  10. Typically, spark plugs don’t need to be replaced until around 80,000 miles, but if you notice any of these symptoms, it’s time to get them checked out.


In this article, we covered a lot when it comes to spark plugs. First, we learned how plugs work in practice and we also covered the symptoms of bad plugs. Things like misfires, low engine power, inability to start. These things should be your top triggers when it comes to spark plug failure.

Then we answered the question of how long spark plugs last. And we learned that they are pretty much bulletproof for about 60,000 miles. Unless there are other factors that can damage them and make them foul. Lastly, we learned how you can replace the spark plugs on your car with only a socket and a wrench.

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