Signs I Need New Spark Plugs in My Engine

You will need new spark plugs in your engine anywhere from 30,000 miles to 100,000 miles. It depends on the age of your vehicle and the types of plugs that are installed. We can check your plugs if you have any of the problems listed below. If they are worn, we will replace them. One way to ensure that you always have functioning spark plugs is to bring your vehicle to our shop for the factory-scheduled services.

Hard/No Starts

When you turn the ignition key or press the start button, the starter turns over the engine. It does this so the engine can bring fuel and air into the cylinders. Next, the starter sends electricity through the plug wires to the spark plugs. This causes the spark plugs to generate sparks in the cylinders. This ignites the air and fuel and starts your engine. If your spark plugs are worn out, they may not generate sparks and it will be difficult if not impossible to start your engine.


Even if you do get the engine started, you may run into problems with it misfiring and stalling. The spark plugs continue to fire while the engine is running. The air and fuel are replenished in the cylinders and burned by the spark plugs. This constant cycle is called combustion. Worn spark plugs affect the engine’s ability to produce combustion and cause the cylinder block to misfire.

Rough Idling

Your engine may also stall because the idle is too rough. Again, this is happening because the cylinder block is misfiring. In other words, your car, truck, or utility vehicle is not firing on all cylinders. The rough idle will make your engine cut out and your vehicle shake.


Worn spark plugs can also affect the performance of the engine when your vehicle is in motion. For example, if the plugs are producing too many sparks, your engine will surge and your automobile will pick up speed by itself. If the plugs are not producing enough sparks, the engine and acceleration will lag.

Poor Fuel Efficiency

Unfortunately, this means that the worn spark plugs will indirectly cause poor fuel efficiency in your automobile. The engine will increase its fuel consumption as it struggles to produce power. If the engine is surging, it is burning extra fuel. Either way, you will head to the service station more often.

If it has been more than 30,000 miles since you have had your engine checked, call our shop today to schedule a service visit.

Call Fairfax Auto Repair at 703-822-5911 for an appointment today!

Photo by EkaterinaZakharova from Getty Images via Canva Pro

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