Spark Plug Replacement Cost
Spark plug replacement costs $80–$440 depending on how many plugs your engine has, the type of plugs, and how accessible they are. It's a key maintenance item that directly affects fuel economy and engine performance.
Average Cost
- 4-cylinder engine: $80–$180
- V6 engine: $120–$300
- V8 engine: $150–$440
- Labor is a major cost driver — some V6 engines (like the Honda Accord V6) require intake manifold removal, adding hours of labor
Spark Plug Lifespan by Type
- Copper plugs: 20,000–30,000 miles
- Platinum plugs: 60,000–80,000 miles
- Iridium plugs: 80,000–120,000 miles
- Double-platinum/iridium: up to 120,000 miles
- Most modern cars use iridium and should follow the manufacturer's interval, not change early
Signs of Worn Spark Plugs
- Rough idle or engine misfires (check engine light may appear)
- Poor fuel economy
- Sluggish acceleration
- Hard starting, especially when cold
- P030X misfire codes (P0301, P0302, etc.)
Why Some Engines Cost More
Spark plug access varies enormously by engine design. A simple 4-cylinder with plugs on top of the engine takes 30 minutes. A transverse-mounted V6 with plugs on the firewall side may require removing the intake manifold — a 4–6 hour job. The Ford 4.6L/5.4L V8 has a notorious two-piece plug design that can break off in the head, turning a $200 job into a $1,000+ repair. Always use the correct OEM-specified plug.
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