How Often Should You Change Your Spark Plugs? Signs to Look For, Tips, & More

Whether you’re accustomed to paying new car prices or used car values when you purchase and price a vehicle, how often to change spark plugs is a vital aspect of car ownership every driver needs to know. Your car engine depends daily on spark plugs to operate.

Like you wouldn’t leave home without insurance or an emergency kit in your vehicle, getting behind the wheel with a failing spark plug could spell equally disastrous effects. From poor engine performance to lessened fuel economy, being able to recognize the signs of a failing spark plug and knowing how often to change spark plugs is crucial.

Here’s what you need to know.

Why Do Spark Plugs Matter?

Unless you’re the proud owner of an electric vehicle, spark plugs are going to be an integral part of your life as a car owner. Your vehicle contains an internal combustion engine known as ICE for short. These combustion components depend on the presence of a spark.

Spark plugs are an integral part of your car engine’s operation because they are responsible for producing that combustion, during both the ignition activation and as the engine progresses through cycles of combustion when you drive your vehicle. If your spark plugs aren’t functioning correctly, your engine won’t operate at maximum combustion level, which can hurt fuel usage to engine operation to acceleration power.

The Top Signs of Failing Spark Plugs

Here are some top signs to look for if you’re concerned that your spark plugs could be on the fritz:

  • Your car is accelerating too slowly and operating sluggishly
  • You’ve noticed that your vehicle isn’t economizing fuel like it used to
  • The engine is misfiring
  • You’re having trouble starting your car

How Often Should You Change Your Spark Plugs?

You should typically change your spark plugs according to the frequency directed by your car owner’s manual, which usually hits in the ballpark of 30,000 miles. If your owner manual doesn’t instruct you when you should switch out your existing spark plugs for new ones, if you don’t know the last time someone put spark plugs in your new vehicle, or you’ve noticed any of the signs of a failing spark plug, it’s time to change them.

If anything about your engine seems off, the first component you should look into are the spark plugs. Take a look at your car owner’s manual or use a car finder to see where the spark plugs are in your vehicle, then check beneath the hood to see what’s happening for yourself. If your spark plugs look dirty, this could be a signal that you have carbon deposits or an oil leak. Spark plugs that look worn or damaged could mean that your engine is misfiring or operating at excess heat levels.

As a rule of thumb, you should replace your spark plugs in intervals of 20,000 to 40,000 miles, based on how often you use your vehicle and the kind of car that you drive. For example, if you own a high-performance car, you’ll need to change your spark plugs more frequently than you would with a vehicle featuring lower revs and more moderate performance.

How Much Does It Cost to Change Spark Plugs?

The excellent news for car owners everywhere is that changing your vehicle’s spark plugs won’t break the bank. Spark plugs cost between $16 and $100 out of pocket. If you opt to pay a professional to change your spark plugs, the shop will charge you anywhere from $40 to $150 for labor.

If you’re brand new to spark plugs and have never changed them out before, you may prefer to hire a professional to make the switch. However, with the right tools and some time, it is possible to replace your vehicle’s spark plugs on your own at home.

How to Change The Spark Plugs in Your Vehicle

Depending on the type of spark plug you have, you might need a spark plug socket specific to that component. To change the spark plugs in your car, you’ll need:

  • A socket wrench
  • A gap gauge
  • Spark plug wire puller
  • Torque wrench
  • Swivel socket
  • Needle-nose pliers
  • Rags to wipe up grease and oil

Begin by taking off the plastic cover on the spark plug and air cleaner component from the top of your engine. If you have to take out vacuum hoses, label them so you can reinstall later without issue. Clean the top of your engine if you have a four-cylinder (if you have a V engine you’ll clean the banks area) before you take out any other parts.

Blow compressed air on the ignition coils so dirt and debris don’t fall in the cylinders. Next, remove your ignition coil be pulling the locking tab. Take the connector of your coil and disconnect the coil bolt so you can remove the whole coil and boot component. If your vehicle doesn’t feature a COP ignition, the spark plug wire will have a boot connected to the plug so you can use the spark plug wire puller to remove the boot.

Let your engine cool down before you remove the spark plugs. Take your spark plug wire puller, position the boot far down to the end of the plug, twist it, and remove with counter-clockwise rotating motions. Use your swivel socket as needed. You’ll also want to gap your new spark plugs before you install them according to the manufacturer’s instructions.

Use a torque wrench based only on the manufacturer's torque specs to ensure you have the proper amount of torque, as too much will misshape the plug. Finally, remember to apply lube to the boot of the new spark plug before you reinstall the coil to inhibit misfires and make any future changes easier. Reinstall your coil, electrical connector, and bolt, then install the vanity cover and air cleaner. Now, you should be all set and ready to fire your engine up.