Virginia Auto Service

5 Signs That Your Spark Plugs Need Replaced

How often do you think about your spark plugs? If you are like most people, chances are it’s not very often. Though often overlooked by car owners, the spark plug is an important component of any finely tuned engine. The condition of the spark plugs can affect the power that your engine puts out, how good your fuel economy will be, and how smoothly your engine runs. Like your car’s oil, and other important parts, the spark plugs should be maintained and changed when necessary.

5 Signs that Your Spark Plugs Need Replaced

What is a spark plug?

Spark plugs are a fundamental part of the ignition system. They screw into the top of an engine’s cylinders where they receive a high voltage electrical current from the ignition coil(s). They then create the electric spark that is required to ignite the compressed air-fuel mixture in the combustion chamber. They will also transfer heat away from the combustion chamber. These events happen over a thousand times per minute when you are driving. It is this constant ignition that keeps your car moving on the road. The number of spark plugs your car has depends on how many cylinders there are. If you have a four-cylinder engine, you will have four spark plugs, and so on.

How do you know if your spark plugs need replaced?

Preventative maintenance is key to the over-all health of your vehicle. The spark plugs are no exception. Spark plugs usually need to be changed every 30,000 miles. There are, however, some high-performance plugs that can last as long as 100,000 miles. You should always check your owner’s manual for your vehicles specifics. When you replace your spark plugs, you should use the same type of spark plug that your car was originally equipped with. For example, if it has double platinum spark plugs originally, then double platinum spark plugs should be used to replace them, as this is what the vehicle manufacturer intended the vehicle to use. If you notice that your fuel economy has decreased, or that your engine runs roughly, or you are driving a vehicle with a lot of miles and simply don’t know the last time they were changed, your engine could probably benefit from new spark plugs.


Here are five signs that your spark plugs need replaced:

  1. Trouble starting your car

Most people are not aware that having worn spark plugs can cause their car to have troubles when starting. Usually they assume it is a flat battery or being out of fuel. Having worn spark plugs will cause the ignition system to work harder.  Faulty spark plugs can also cause your battery to drain. Harsh weather conditions increase the chance of worn spark plugs preventing the engine from turning over. If you notice your car struggling to start, you may want to take a look at the spark plugs as a possible cause.

  1. Engine misfire

It is easily recognizable when an engine misfires. A misfire causes the car to halt for a split second then it continues on at its normal pace. How serious your misfire problem is will determine how often this will happen. Engine misfire means that the vehicle is not functioning as well as it should because one or more of its spark plugs aren’t firing properly. This could lead to a reduction in fuel economy, reduced engine power, or increased exhaust emissions.

  1. You notice a rough idle

Idling occurs when your car is stationary, yet the engine is running. While idling, your engine runs at a lower RPM. When an engine has spark plugs that are performing properly, the sound should be continuous and smooth. When they are not working as they should, the engine will sound jittery and rough and it will stumble and produce a vibration that can be felt throughout your vehicle. You need to have this checked right away as ignoring this symptom can lead to costly and serious damage being done to your car.

  1. Poor acceleration

It is easy to tell if your vehicle is accelerating poorly. When you put your foot down on the gas and it feels like it doesn’t want to respond, or it does, but slower than normal you are experiencing symptoms of poor acceleration. Your car may also feel like it is trying extra hard to move. You may find that servicing your vehicle with a spark plug change fixes this sluggish feeling.

  1. Consuming more fuel

Having spark plugs that function properly help keep the emissions coming from your vehicle at a minimum. Spark plugs that are deteriorated can lead to a decrease in your vehicle’s fuel economy due to incomplete combustion. So if you notice that you are filling up more often, have your spark plugs checked.


If you are experiencing any of the above symptoms, or have any other vehicle related concerns please call us at 602-266-0200. We here at Virginia Auto Service are happy to help you with your car care needs.