How to tell if you Need New Spark Plugs

Spark plugs are an essential element for the correct operation of any car with a gasoline engine. They are as old as the automobile itself, and without them the explosion of the gasoline-air mixture inside the combustion chambers could not take place.

The spark plug spark is a simple arc between two electrodes, produced by the passage of electric current through them. They are absurdly simple and reliable, but they are components subject to constant wear and tear, and must be replaced according to your car manufacturer’s specifications.

When Do I Have To Change The Spark Plugs In My Car?

The answer is clear: it depends. Spark plugs have a limited life, but their life can vary from the mere 20,000 km or 30,000 km of the old copper-core spark plugs to the 120,000 km or 160,000 km of modern spark plugs with platinum or iridium cores.

The answer to the question is in your car’s owner’s manual, where you can find the recommended replacement interval for the spark plugs. The lower end of the spark plug is in the combustion chamber itself, and is constantly subjected to very high temperatures and pressures, so wear is inevitable.

That’s why we advise you when you should know it’s time to replace your old spark plug with a new one. Take a look at these simple signs.

Symptoms That Your Spark Plugs Need Replacing

1. Check Engine Light

If you are familiar with automotive engine problems, you will know when it is time to change the spark plugs. The fundamental indicator you will get when changing the spark plug is to check the engine light. If you discover a faulty spark plug, you should first check the check engine indicator light. If the check engine light comes on, you should assume there is a problem with the spark plug. Also, the check engine light may flicker at times. In this case, you should inspect and perhaps replace the spark plug to improve the engine.

You may be involved in an accident if you do not inspect the check engine light problem caused by the obsolete spark plug. Engine fires are a typical occurrence if you are not cautious. This can also cause the check engine light to come on. When you notice the check engine light flashing, you should recognize that this is a warning indication of a possible disastrous fire.

All you need to do in this scenario is replace the spark plug. In contrast to a catastrophic engine fire, this will decrease your losses. If you find yourself in this situation, we suggest that you replace the spark plug early as a precautionary measure. The manufacturer’s specifications are sufficient for this purpose. Misfiring can also put a strain on the engine’s exhaust filter.

2. Gas Tank requires more Gas

When your car’s spark plug reaches the end of its service life, you may notice that your fuel mileage isn’t as good as it used to be. The spark plug will eventually omit you from your vehicle’s fuel mileage. The use of the spark plug in a car has a direct impact on the fuel tank.

As a result, your vehicle’s fuel consumption will skyrocket. The reason for this is that the gasoline entering the engine cannot be burned efficiently. As a result, you will notice a greater need to fill the tank.

In addition, the cost of refueling your car will increase. In this situation, you should know that the worn spark plug must be replaced.

3. Starting takes time

One of the most typical difficulties with automobiles is that the engine is slow to start. There can be several causes for your car to start. However, one of them is missing spark plugs. Spark plugs are critical components of your engine. One of the most important functions of spark plugs is to generate sparks in the engine so that it can start.

If the spark plug’s function is to create sparks, and the spark plugs are worn out, how do they work? They won’t be able to work if they can’t acquire food for a few days – your engine won’t start if there are no sparks! I guess it’s simple!

When spark plugs are worn, they take too long to create sparks, which in turn provides the sparks needed to properly drive the engine. If you open the vehicle and find that it has stalled, it is likely that the spark plug has broken. Replace the spark plug as soon as possible.

4. Late Acceleration

You know how the car performs as your driving time increases. If one day you travel on the road, you will notice that the car does not respond as before, and now you have to take the necessary measures.

If you do not understand this fact, you should pay attention to the acceleration of the car. If you find that you cannot accelerate your vehicle as before, it is likely that your car’s spark plug is broken. You don’t want a slow, gas-guzzling car, do you? Replace the spark plug.

5. Rough Engine

Most of the time, engine noise is quiet and not too loud. If you have a vehicle, you are familiar with the sound of the engine starting and driving. However, if the spark plug is broken or worn, the situation will change.

If it purrs like a cat all the time and then stalls, the spark plug is to blame. All you have to do is turn off the music and pay close attention to the engine. If you notice that the engine is too noisy, or if it rattles or forks, it’s time to change the spark plug.

If the spark plug isn’t working properly, you might hear a knock at the door. Replace the old spark plugs with modern spark plugs to get back to a smooth, low-noise ride.

6. Manufacturer Recommendation

When you buy a car, the manufacturer provides you with all the vehicle specifications. The manufacturer’s recommendations include everything you need to know, from head to toe, engine to tires. You will also see here the manufacturer’s suggested service interval. This section contains the vehicle’s suggested maintenance schedule.

With the help of the tutorial you will be able to realize when to change the spark plug. Accordingly, you should be able to change it without incident!

What Happens If I Do Not Change The Spark Plugs?

As is the case when the oil change is overdone, the engine will not stop running or suffer a catastrophic failure, but we do run a greater risk of being left stranded, or causing a major breakdown. The “best” case scenario is that of a spark plug with a worn spark plug tip will cause ignition interruptions, which will be perceived as vibrations or irregular idling. In case of complete spark plug failure, the engine fault indicator will most likely light up and the cylinder in which the spark plug is mounted will stop working.

In a four-cylinder engine the car will run on three cylinders, with a much worse sound, jerks and jolts, and in general a clearly defective behavior. We may even have problems starting the engine. Replacing the spark plugs, a simple and inexpensive task, would nip these problems in the bud. However, we may not have these symptoms and continue to use spark plugs whose service life is far behind. If we do so, we risk the ceramic insulator of the center electrode itself breaking, or the ground electrode itself splitting.

And then we will have a much more serious problem, because these pieces of ceramic or metal will fall into the combustion chamber. If a piece of spark plug breaks off, it will scratch the walls of the combustion chamber and can break the piston rings. It could even affect the valves and the piston head itself, causing a costly failure. Keep in mind that the linear velocity of the pistons of an engine is tens of meters per second (hundreds of kilometers per hour). All this for not changing a wear part whose price can be as little as three euros.

Final Thoughts

If your spark plug is worn out, it can be quite dangerous for you and your car. A faulty spark plug can cause the vehicle to catch fire. If you choose to ignore it, replace the spark plug before something terrible happens.

Fortunately, spark plugs are inexpensive. The vast majority of cars have only one spark plug per cylinder, but some cars with “twin spark” engines – also called dual ignition – have two spark plugs per cylinder. The best known twin-plug engines are those made years ago by Alfa Romeo, but twin-plug engines also exist in Mercedes or Nissan. Dual ignition is quite common in the motorcycle world.

If you are still not sure how to tell if you need new spark plugs, you should follow the methods we have provided. With all this in mind, you’ll be able to know when to make the necessary modifications!

Have you ever had a major spark plug problem? Please share your thoughts in the comments section!


Hi, I'm the initiator and writer of this blog. Cars were and will be my first love, and my favorite hobby, that's why I decided to start this blog and write about my discoveries and techniques to improve my cars or repair them.