HomeCar RepairWhen to Change Spark Plugs? (7 Common Symptoms)

When to Change Spark Plugs? (7 Common Symptoms)




It is not an easy thing to maintain your car properly. There are a number of things to take control of, and nothing should be taken lightly, including the smallest parts of your car. For instance, spark plugs are a vital part of your car’s performance. These plugs can lead to damage if they erode and create a gap without being replaced. As spark plugs become older, they lose their sharp edges as material from the center and ground electrodes is slowly eroded away. This, in turn, creates a wider gap between these two points making the plugs to be less effective in performance. To know when to change your spark plugs, here are the various signs to look for.

When to Change Spark Plugs?

Most of the spark plugs have a life expectancy of around 45 000 miles, and some manufacturers state their spark plugs to have a life expectancy of 100 000 miles. You shouldn’t wait for the spark plugs to reach their life expectancy before changing them. Facing trouble while starting the car is one of the major signs of a faulty spark plug. There are also some other signs including, engine misfire, poor mileage, rough acceleration, and more. Worn ground electrode and Iridium tip is the main reason for a fouled spark plug. So if you notice any of these listed signs while driving your vehicle, change your spark plug immediately.

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You have difficulty starting your vehicle

A good number of people think that their car having starting difficulties is as a result of it running out of fuel or having a flat battery. This isn’t usually the case, as a bad or worn-out plug may be the cause. In the situation where the spark plugs don’t produce the sparks needed to start your car, it won’t move at all. In addition, faulty spark plugs can cause your battery to drain. If this is the case, then you will be needed to change the spark plugs in your car and the car battery, too.

The engine has a rough idle

When in the stationary state, the engine idles, and in this position, it usually produces around 1000rpm. If your spark plugs produce a rough and jittery sound instead of a constant and smooth sound, then you should replace them. Get your car checked and repaired quickly to avoid further damages. It also helps maintain the car engine healthy and smooth.

Engine surge

Engine power surges are indications of your vehicle’s engine not functioning effectively. This can be really dangerous if such a sign takes place when you are in traffic. When you realize such a sign, you should have your car inspected by a professional mechanic and the issue repaired. Probably, you should buy and replace spark plugs.

High fuel consumption

When the spark plugs are in bad shape, you will realize that your vehicle’s fuel economy can decrease by up to 30% as a result of incomplete combustion. The moment you realize that you’ve to fill up your fuel tank more often than usual, then it may be because of bad spark plugs. These should be changed with new ones.

Your vehicle’s engine misfires

Engine misfire is a common engine problem that makes the car stop for a fraction of a second and then continue its normal movement. This implies that the car isn’t working as efficiently as it is supposed to, with one or more cylinders failing to fire well. This can also lead to greater amounts of emissions.

Lack of acceleration

When your car is accelerating poorly, then it is very easy to tell. This is because the car feels as if it doesn’t want to respond when you place your foot down. Sometimes, it can feel as if your car is trying very hard to pull itself along. All of this can be caused by a bad spark plug.

Oil leak

When the spark plug is pulled out of the engine, the base is needed to be clean. In case you note the presence of oil at the base, then there is a leak. This as well implies that you have a seal that needs to be replaced, but also, your spark plugs will require to be changed frequently.

Related article: Signs That Indicates Your Car Needs an Oil Change

Spark Plug Changing Cost

Replacing spark plugs won’t cost you a lot of money if you do it yourself. Generally, there are two types of spark plug found in the market, and they are  Conventional spark plugs and iridium spark plugs. A Conventional spark plug would cost you only 5$-15$. On the other hand, a Platinum or iridium spark plug would cost you around 15$-50$. Additional 150$-250$ will be added if you made it done by a professional mechanic.


Spark plugs a huge component of the Car system. When you note one of the signs that we’ve just discussed above, you should change them instantly so that your vehicle can perform exceptionally. Visit a professional mechanic if you can’t replace them by yourself.


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