📋 Typical Lifespan
Miles
30,000–100,000
Years
4–8
Replace
$100–$350
Copper plugs last about 30,000 miles. Platinum plugs go 60,000 to 80,000. Iridium plugs are typically rated for 80,000 to 100,000 miles.
⚠ What Shortens Spark plugs Life
- Plug material - iridium and ruthenium outlast copper several times over
- Running rich from a leaking injector or bad O2 sensor (fouls plugs fast)
- Burning oil from worn valve seals or piston rings
- Towing or sustained high-RPM driving
- Incorrect gap or torque on installation
🔍 Signs It's Failing
- Rough idle that smooths out at speed
- Misfire codes P0300 through P0308
- Hesitation or jerking on acceleration
- Worse fuel economy than usual
- Hard starts, especially in cold or damp weather
- Check engine light flashing - this means active misfire, stop driving
Deeper dive: Rough idle that smooths out at speed and other spark plugs failure symptoms.
💵 Replacement Cost
$100 to $350 is the typical range for parts and labor on a mainstream vehicle in 2026. Luxury, European, and AWD layouts can run 30 to 50 percent higher.
Plugs cost $4 to $12 each. Labor varies from 30 minutes on a 4-cylinder to 3+ hours on V6 and V8 engines that require intake removal.
💡 Get a vehicle-specific estimateOur AI report ranks the most likely failure points for your exact year/make/model and gives parts pricing in your zip code.
❓ Frequently Asked Questions
Should I replace all plugs at once?
Always. They wear together and a single new plug next to old ones will run differently and trip a misfire code.
Do I need to gap iridium plugs?
Most come pre-gapped from the factory. Check anyway - shipping damage happens. Use a wire gauge, never a coin gauge, on fine-electrode plugs.
Can the wrong plug damage my engine?
Yes. Heat range that is too cold fouls; too hot can preignite and crack a piston. Always use the manufacturer-spec plug.
Why is my engine misfiring after a plug change?
Either a damaged plug from over-tightening, a cracked porcelain insulator, a loose coil-on-plug boot, or carbon-tracking inside an old coil that the new plug exposed.
How do I make spark plugs last longer?
Fix oil burning, fix rich-running fuel system issues, and avoid prolonged idling. Plugs that stay clean and dry hit their rated mileage easily.
Does premium fuel make plugs last longer?
Not directly. Premium only helps if your engine specifies it - otherwise it just costs more for no benefit. Detergent levels matter more than octane for plug life.