Written by: Jen Wagner
Last updated: March 11, 2023
Routine maintenance is a critical part of car ownership that helps increase longevity, improve fuel economy and performance, and promote safe driving. But, like most machines, car parts deteriorate over time, eventually requiring repair or replacement. One such component is your car’s spark plugs. Yet knowing when to replace them can be complex, primarily because the answer often lies in the details. So what are those details exactly?
Understanding What Spark Plugs Do
All car parts have a specific function and fall into certain categories or systems. A car’s spark plugs are part of a vehicle’s ignition system. They are the devices that screw into an engine’s cylinders and change high-voltage electricity from the ignition coils into a spark. The electric “spark” ignites the air/fuel mixture inside the engine cylinder, creating a build-up or small explosion that pushes down the cylinders and allows the engine to start and run.
A car, however, is inoperable without working spark plugs to ignite the fuel and start the engine. Also, driving when they are worn can weaken the car battery and damage the engine. Therefore, knowing how often to replace your spark plugs and recognizing when they might fail becomes even more necessary to ensure proper vehicle function and prevent total failure. Where can you find information on when they need changing? Start by looking inside your glove compartment for the factory owner’s manual.
Determining When to Replace Spark Plugs
Anytime you buy a car, the owner’s manual should be your first resource for seeking answers to questions and concerns. The handbook will provide information on safety features, controls, and mileage guidelines for various part replacements. Sometimes, one of these components is a spark plug. Depending on your car’s make and model, the automakers may advise replacing them when you reach 18,000 miles, 35,000 miles, or even 100,000. Auto websites like RepairPal and AutoZone note that spark plug failure can occur around 100,000 miles of use when a vehicle is driven under normal conditions. Yet extreme conditions like excessive heat, frigid temperatures, or prolonged idling can cause more rapid deterioration.
In addition to what you drive, the type of spark plug your vehicle uses is another determining factor for when you need to replace them. Some cars use copper or nickel spark plugs, which wear more quickly and require changing every 30,000 to 50,000 miles. Other vehicles use ones made with platinum or iridium, which are more durable and last longer. Therefore, checking your owner’s manual and educating yourself on your spark plug’s lifespan can help ensure the components stay in peak operating condition. Should your manufacturer recommend more frequent replacements, keeping a car maintenance log can be a valuable tool to track the next time you’re due for a new set.
But what about when something goes wrong before reaching the recommended mileage? Are there signs you can look for that point to spark plug problems? Absolutely!
Recognizing the Signs of Bad Spark Plugs
While the frequency in which you replace your spark plugs depends on several factors, there are several signs you can look for that suggest your spark plugs are failing. If you suspect a spark plug problem, look for the following red flags:
- Your check engine light turns on.
- The engine has difficulty starting.
- You feel rough vibrations when your car is running or idling.
- The engine misfires, causing a sputtering sound.
- You notice an increase in exhaust fumes and gas odors.
- Your gas tank drains faster than usual, signifying a decrease in fuel economy.
If you encounter any of the above signs, getting your car to a skilled auto technician as soon as possible is advisable to help prevent further decline in vehicle performance and fuel economy. Why? Well, when spark plugs stop working, more problems arise. For instance, an engine’s fuel stops burning, increasing the likelihood of it leaking into the exhaust system, ruining the catalytic converter, and causing a hefty repair—between $1,996 and $2,073 to fix it. Hence, you want to fix the problem ASAP before worse issues result.
Paying for Spark Plug Replacements
Now that you understand what spark plugs do and the signs you might notice when yours fail, what can you expect to pay for replacements? Again, the answer depends on a few factors, including the type of spark plugs your car uses and who you choose to replace them. According to AutoZone, a single spark plug can cost between $3-30, with an average rate falling around $15. But if your car uses high-performance spark plugs, you can expect to pay much more—upwards of a couple hundred dollars. Knowing someone who can replace them for free or doing it yourself, however, can save you $50-200 on labor costs.
Saving on Repair Bills with an Auto Warranty
Wear and tear is a natural part of car ownership. But when you stay on top of routine maintenance and learn the warning signs of a breakdown, you can help extend the life of your car and prevent more rapid deterioration. Start protecting your vehicle and budget today by investing in a vehicle protection plan with a top-rated provider. While not every business offers wear-and-tear coverage, some do. But before signing an agreement, study the terms so you know everything it covers and excludes beforehand. Check our extended car warranty list for information on the top plans and providers in the industry.
