Spark plugs are a critical part of keeping your engine running properly. They ignite the air-fuel mixture inside each cylinder, firing thousands of times every minute while you drive. As they wear out, you may start noticing changes in how your vehicle performs.
How long do spark plugs last, and how can you tell when it’s time to replace them? Here’s what you need to know.
What Do Spark Plugs Actually Do?
Each spark plug sits inside a cylinder and creates the spark that ignites the compressed air and fuel. This combustion is what powers your engine and keeps your car moving. Without properly working spark plugs, your engine may misfire, struggle to start, or run less efficiently.
A healthy spark plug ensures the engine fires correctly, delivers maximum power, and keeps emissions in check.
Typical Spark Plug Lifespan
The lifespan of spark plugs depends largely on the type of plugs your engine uses:
- Copper spark plugs generally last around 20,000 to 30,000 miles.
- Platinum spark plugs tend to last between 60,000 and 100,000 miles.
- Iridium spark plugs, commonly found in newer vehicles, often last up to 100,000 miles or more.
While those are good estimates, actual life can vary depending on driving habits, engine type, and how well your vehicle is maintained. Short trips, stop-and-go traffic, or engine performance issues can all cause plugs to wear out faster.
Signs Your Spark Plugs Might Be Worn Out
If your spark plugs are nearing the end of their lifespan, your car will usually start showing some symptoms. These may include:
- Engine misfires or a rough idle
- Decreased fuel efficiency
- Sluggish acceleration or lack of power
- Trouble starting the car
- Check engine light coming on (especially for misfire codes)
You may also notice that your vehicle vibrates more at idle or that it hesitates when you step on the gas. All of these signs can indicate that the plugs aren’t firing consistently or completely.
What Happens If You Wait Too Long
Delaying spark plug replacement can lead to more than just reduced performance. Misfiring cylinders can damage ignition coils, increase emissions, and overwork the catalytic converter. In extreme cases, your engine may start to run so poorly that it risks stalling—or not starting at all.
Replacing spark plugs on schedule helps protect the rest of your engine from unnecessary strain and damage.
Should You Replace All Spark Plugs at Once
Yes. Even if only one plug seems bad, it’s best to replace them all at the same time—especially if they’ve all been in the engine for the same length of time. Installing a fresh set ensures even performance across all cylinders and helps you avoid another trip to the shop shortly after.
It’s also a good time to inspect the ignition coils, wires (if applicable), and check for oil leaks near the plug wells.
How to Keep Your Spark Plugs Lasting Longer
Routine maintenance plays a big part in spark plug longevity. Keeping your fuel and air filters clean, maintaining proper engine timing, and avoiding excessive idling all help reduce wear on plugs. Using high-quality fuel can also minimize carbon deposits, which tend to build up on older plugs.
If your engine burns oil or runs rich, addressing those issues early will also help your plugs perform better and last longer.
Complete Car Care Encinitas – Spark Plug Service You Can Trust in Encinitas, CA
At Complete Car Care Encinitas in Encinitas, CA, we can get the most from your vehicle with expert spark plug service. Whether you're due for a tune-up or just want to keep your engine running at its best, our team is here to help. Book your spark plug replacement today and enjoy smoother starts, better mileage, and improved performance.