A car engine spark plug is a small component, but it has a major responsibility and a direct effect on engine performance. It has a limited service life, after which it must be replaced with a new plug.
When the spark plug can no longer perform properly, various engine problems will appear, and by paying attention to these symptoms you will realize that it is time to replace it. In the following, we will look at the key signs that indicate the spark plugs have reached the end of their service life.
Check engine light comes on
Corrosion or wear of the spark plug, especially in modern vehicles, can be accompanied by illumination of the check engine light. If the check engine light starts flashing, replace the spark plugs immediately, as there is a risk of serious damage. It is recommended to replace the spark plugs regularly and after a specific mileage according to the manufacturer’s instructions so that this relatively low‑cost part does not lead to higher repair expenses.
Rough or unstable idle
An irregular engine idle when the car is running at a standstill, and even excessive exhaust emissions, can be a sign that the spark plugs are worn out.
Hard starting
The main role of the spark plug is to ignite the air–fuel mixture and generate power for the engine. An old or corroded plug struggles to do its job properly. If your car has difficulty starting and does not crank or fire up as smoothly as usual, you probably need to replace the spark plugs. Of course, the battery also affects starting, so first make sure the battery is properly charged.
Increased fuel consumption
If the spark plugs are old or worn, they cannot ignite the fuel–air mixture efficiently in the combustion chamber. This poor combustion performance can lead to higher fuel consumption. So if you find yourself visiting the gas station more often than normal, it is a good idea to check the spark plugs.
Engine vibration
Since a fault in the spark plugs disrupts the combustion process, it can cause knocking, vibration, and unusual noises from the engine. If you notice these symptoms, inspect the spark plugs.
Poor acceleration
You are familiar with how your car normally accelerates and responds to throttle input. If acceleration feels weaker than usual or the vehicle responds sluggishly, check the spark plugs and replace them if necessary.
