Can You Replace Just One Spark Plug – Step by Step

Can You Replace Just One Spark Plug

On one fine morning, you get ready for your office and go out only to find out that your car engine isn’t starting at all. You might discover that the problem is in one of your spark plugs.

Now you’re probably thinking, can you replace just one spark plug, or do you need to change all of them?

The simple answer is yes, and you can change only one worn-out spark plug as a quick fix. However, you should change all your spark plugs at once so that your car’s engine can give you the best performance.

Let’s dive deep into the topic and find out more about the functions of spark plugs. We will also discuss when and how you can replace a spark plug in some easy steps.

How To Replace a Spark Plug – 4 Steps Guide

In case you have previous experience changing the parts of a car engine, you might be able to change the spark plugs of your car all by yourself. Here’s how you can install new spark plugs

Step 1) First, wipe the spark plug hole clean with a cloth to ensure no grease, oil, or dirt is left inside. Then lightly apply some oil to the threads of the new spark plug

Step 2) Now, you need to seat the spark plug inside the engine. For this, use your hands for threading the plug inside the hole while you turn it in the anti-clockwise direction. You need to perform two full turns to fit the plug snugly.

Step 3) Place the spark plug socket on the plug and use a torque wrench to turn the spark plug clockwise to achieve a tight fit. Do not overtighten it as you might crack the porcelain otherwise.

Step 4) Replace the spark plug wire as well if it seems frayed or cracked. Apply some lubricant on the boot, and then place it on your new spark plug terminal. Once you have pressed the boot firmly in its place, your job is done!

What Do Spark Plugs Do Inside Your Car Engine

The engine of your car uses petrol or gasoline to produce the kinetic energy that runs the entire car. Spark plugs remain inside your car engine to provide the necessary spark that ignites the air and petrol mixture.

It results in an explosion inside the car cylinder, and the produced energy allows your car engine to drive your car forward. To ignite the mixture of air and fuel, spark plugs can spark around 10,000 to 30,000 volts depending on the type of car motor.

Generally, spark plugs are made of highly durable materials that can survive millions of explosions. High-quality spark plugs usually have a shelf life of approximately 100,000 miles or more.

However, the plugs start to corrode after 30,000 miles and need to be replaced to maintain the performance, and efficiency of your car engine.

Here are some issues you’ll face if you don’t change worn-out spark plugs timely-

  • Your car engine will stop running, or it will run less smoothly
  • Idling or stalling will be unstable
  • The fuel economy of your engine will decrease
  • You might face the problem of unresponsive acceleration

How Many Spark Plugs in A v8 Engine

Typically, a car will have one spark plug for each cylinder. Hence, if you have a v4 engine with 4 cylinders, your car will have 4 spark plugs. Just like that, a v8 car engine has 8 cylinders and 8 spark plugs for each cylinder.

However, many manufacturers use advanced technologies like twin spark and double ignition in their v8 engines, which require more than 8 spark plugs. Similarly, HEMI v8 motors feature 2 spark plugs per cylinder. So, these motors have 16 spark plugs instead of 8.

To find out how many plugs your car engine has, you should count how many spark plug wires are there. For example, if your engine has 8 wires, it means it contains 8 spark plugs.

Is It Okay to Replace a Single Spark Plug

If only one spark plug of your engine is defective, you can replace it while the other ones are still in good condition. But it’s better to replace all the spark plugs at a time because it ensures a smooth and even performance of the engine.

The spark plugs start to deteriorate after a year of use because of constant combustion forces and the accumulation of oil and grease. In case you change only one spark plug, your engine might not receive enough spark to get the car going. Also, you might face the problem of misfiring.

Hence, it’s better to replace all the spark plugs at once to ensure smooth performance and to avoid all kinds of sparking problems in the future.

Spark Plug Replacement Cost Estimation

For most car models, it’s incredibly cheap to replace spark plugs. In fact, a regular spark plug will cost you less than ten dollars. While estimating the total cost, you have to consider the labor cost as well. You can take the car to any garage, and they can replace all your spark plugs within an hour or less.

Typically, you’ll have to pay around $16 to $100 for spark plugs. As for the labor cost, you need to spend around $40 to $150 to replace all the spark plugs. 

So, the total replacement cost will be between $56 and $250 only. Keep in mind that the cost will vary depending on your car model and the material of the new spark plugs.


How often do you need to change spark plugs?

Most manufacturers suggest replacing the spark plugs every 30,000 miles. You can check out the owner’s manual of your car or visit the manufacturer’s website to know the specific distance for a particular model.

What are the symptoms of bad spark plugs?

If your engine starts misfiring, it’s a symptom of defective spark plugs. Sometimes you’ll hear knocking and rattling sounds while you take rough turns. Also, your engine will be less responsive during acceleration. You’ll know it’s time to change the spark plugs when you need to fill the fuel more often.

How much does it cost to replace all your spark plugs?

Replacing your spark plugs is inexpensive, and you’ll need to pay for buying new spark plugs and for replacement labor. It will cost you $16 to $100 for new spark plugs. You have to spend $45 to $150 on the labor cost.


Now you know the answer to the question can you replace just one spark plug or not? Your car will work decently if you only change the one blown-out spark plug.

Yet, we would recommend changing all 6 or 8 spark plugs at once as the costs are low and it will improve the performance of your car engine drastically.

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