When you hear the satisfying roar of your engine, you've got spark plugs to thank. Internal combustion engines use fuel, air and an ignition to turn chemical energy into the mechanical energy that makes your car run. Spark plugs deliver the spark that allows that magic to happen.
If your spark plugs fail, your engine might not turn over, or you may notice it doesn't have much power. Since spark plugs are a wearing part, most people will need to budget for spark plug replacement every few years. Luckily, it's not too expensive.
What are spark plugs?
Any internal combustion engine that runs on gas uses spark plugs. (Diesel engines don't.) Each cylinder in your engine has a spark plug. So, if you drive a four-cylinder sedan, you'll have four spark plugs, while a six-cylinder vehicle will have six and an eight-cylinder will have eight.
Different types of spark plugs
Spark plugs are made from different types of metal. Your vehicle manufacturer's guide will tell you what type of spark plugs you have. The type of spark plugs you have impacts how often they need to be replaced, and how much that will cost.
- Copper spark plugs are cheap but not long-lasting, so they're not used very often these days.
- Platinum spark plugs last longer than copper and are a bit more expensive.
- Iridium spark plugs are very long-lasting, but more expensive than copper or platinum.
- Ruthenium spark plugs claim to be even more long-lasting than iridium, but they're not very common because of their high price.
- Silver spark plugs are found in some performance vehicles, but they're less common because they're not very durable.
How often should you change spark plugs?
Your vehicle manufacturer's guide should mention how often the spark plugs should be replaced. Most vehicles need their spark plugs replaced every 30,000 to 100,000 miles. That's a huge range, so it's always best to check your owner's manual and replace your spark plugs before they begin to fail.
Average costs for spark plug replacement
On average, replacing a vehicle's spark plugs can cost between $211 and $274. But there's a lot that can impact the final cost, including:
| Factor | Description |
|---|---|
| Type of spark plug | Most spark plugs cost about $10, but some can cost more than $25 each. |
| Engine size | Most people opt to replace all their spark plugs at once rather than waiting for each individual spark plug to fail, since when one goes the rest usually aren't far behind. Replacing the spark plugs on a four-cylinder engine will require less labor and materials than replacing spark plugs in a six- or eight-cylinder engine. |
| DIY or professional job | Replacing spark plugs is usually a straightforward job. If you do it yourself—which should take about an hour for a four-cylinder engine—you'll save on labor costs. |
| Layout of your vehicle. | In some vehicles, spark plugs are easier to reach. That cuts down on labor costs. If your spark plugs are harder to reach, you'll have to pay for more time if you're having a mechanic do the job. |
Symptoms of bad spark plugs
It's best practice to change your spark plugs as often as the manufacturer recommends. That's because when spark plugs fail, they can impact your engine function and could even leave you stranded. Still, if you don't know when your vehicle's spark plugs were last replaced, you might need to know some of the signs of bad spark plugs, including:
- Trouble turning over the engine
- Less engine power (which you might notice during acceleration or when traveling uphill)
- Reduced fuel economy, which could have you visiting the gas pump more often
- Engine misfires, which can feel like a jerking motion
- Check engine light, which comes on due to engine misfires
- Maintenance light, which may come on in newer cars when you need new spark plugs
It's best not to put off changing your spark plugs. If a spark plug isn't working properly, it leaves unburned fuel in the engine. Over time, that can damage your catalytic converter, which can cost thousands of dollars to replace.
Should you replace spark plugs yourself?
Replacing your own spark plugs can save you money. Typically, the labor costs for a spark plug replacement are about $129 to $163. But whether it's a good idea depends on your comfort level for DIY automotive projects and the type of car you have. On some models, spark plugs are easy to reach, but on other vehicles, they're more difficult to access.
In any case, you'll need some tools to replace your own spark plugs, including:
- Gap gauge
- Needle-nose pliers
- Socket or ratchet set
- Spark plug wire puller
- Swivel socket
- Torque wrench
The costs of these tools can add up quickly and counteract your savings from doing the work yourself. But if you have the tools on hand or you have a vehicle that needs frequent spark plug replacements, the investment could save you money in the long run.
Save money when replacing your spark plugs
While replacing your spark plugs probably won't break the bank, it's always nice to save on routine maintenance. Here's how to minimize the cost of replacing spark plugs:
- Shop around. Spark plugs themselves are fairly cheap, but you may find a bargain by shopping online. For bigger savings, get multiple quotes on labor, since costs can vary widely from one shop to another.
- Consider DIY. If you're handy, replacing spark plugs yourself can save you a chunk of money, especially if you already have the tools on hand.
- Minimize idle time. Leaving your car idling frequently can wear down your spark plugs quickly and require them to be replaced more often.
- Bundle it with other maintenance. While you're replacing the spark plugs, ask your mechanic whether your coil packs—which provide voltage to the spark plugs—need replacing. This adds hardly any labor cost but can keep your car running well for longer.
- Replace them before they fail. If you wait until spark plugs fail to replace them, you might find yourself paying for a costly tow in addition to the spark plug replacement.
The Synchrony Car CareTM credit card can help you manage spark plug replacement costs
Replacing your spark plugs regularly can help keep your car running well. Vehicle manufacturers will dictate how often your spark plugs should be replaced—usually between 30,000 and 100,000 miles. You should be able to find this information in your owner's manual. Sticking with the recommended replacement schedule can save you costs on towing or more expensive repairs.
The Synchrony Car Care™ credit card can help you manage the cost of spark plug replacement and other routine maintenance. Learn more about the Synchrony Car Care™ credit card and check out the Synchrony partners that can support your smooth travel journey today.
READ MORE: Car Maintenance Checklist