How Often Should Spark Plugs Be Replaced?

Quick answer

Replace copper spark plugs every 30,000 miles and platinum or iridium plugs every 60,000–100,000 miles. Worn plugs cause rough idle, hard starts, misfires and poor fuel economy. Check your owner's manual — many modern engines specify 100,000 miles.

By the ASE-certified team at On-Site Mobile Mechanics of Dallas · 12 years repairing cars across Dallas–Fort Worth

How Often Should Spark Plugs Be Replaced?

Symptoms of worn spark plugs

Rough or shaky idle
Hesitation when accelerating
Lower MPG
Hard starting
Check engine light with misfire codes

Should coils be replaced too?

Not automatically. We test coils and replace only those that are weak or failing.

Cost

Spark plug replacement is typically $120–$480 depending on engine layout; V6 engines with rear plugs cost more.

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