Replacing spark plugs typically costs $100 to $400 at a shop, one of the more affordable tune-up jobs. A set of plugs runs $20 to $120, and labor depends on engine access. Four-cylinder engines are quick, while V6 and V8 engines where the rear plugs are hard to reach cost more.
$100-$400
typical shop cost
$20-$120
plug set (DIY)
0.5-2 hrs
typical labor time
📊 Quick Comparison
Vehicle type
Parts
Labor
Total
Economy 4-cyl
$40
$80
$120
Midsize/SUV V6
$70
$180
$250
Full-size truck V8
$90
$200
$290
European/luxury
$110
$220
$330
What it costs
Spark plug service usually runs $100 to $400. Copper plugs are cheapest but need replacing sooner; iridium and platinum plugs cost more but last 60,000 to 100,000 miles. On some transverse V6 engines, reaching the rear plugs requires removing the intake, which raises labor.
Always use the plug type and gap the manufacturer specifies for reliable performance.
Parts vs labor
The plugs are inexpensive; labor varies most. A four-cylinder is often 30 to 60 minutes; a V6 with buried rear plugs can be two-plus hours.
Copper plugs (set): $10 to $40
Iridium/platinum plugs (set): $40 to $120
Easy-access labor: $60 to $150
Hard-access labor: $150 to $300
Signs you need it
Rough idle, misfires, hard starting, hesitation on acceleration, reduced fuel economy, and a check-engine light for misfire codes can all point to worn plugs. Many are simply replaced on the maintenance schedule.
Rough idle or engine misfire
Hard starting or hesitation
Drop in fuel economy
Misfire codes (P0300 series)
DIY vs shop
On accessible engines, spark plugs are a classic beginner DIY job that saves the whole labor charge. Use a gap gauge, torque the plugs properly, and apply anti-seize only if the manufacturer recommends it. Buried plugs may be worth handing to a shop.
How to save
Buy the correct iridium or platinum plugs and do them yourself if access is easy. Replace ignition coil boots or wires only if they are cracked. Do not overtighten, which can damage the threads in the head.
📋 Never get charged $800 for a $50 fix
The 50 most common check engine codes with likely cause and DIY fix cost. Sent once.
❓ FAQ
How often should spark plugs be replaced?
Copper plugs about every 30,000 miles; iridium and platinum plugs every 60,000 to 100,000 miles. Check your owner's manual for the exact interval.
Can I use any spark plug?
No. Use the type, heat range, and gap the manufacturer specifies. The wrong plug can cause misfires or engine damage.
Do I need to replace ignition coils too?
Only if a coil is failing. Plugs and coils are separate; replace coils when they crack or throw misfire codes, not automatically.
Will new spark plugs improve gas mileage?
If the old plugs were worn and misfiring, fresh plugs can restore lost economy and smoothness. On healthy plugs the gain is minimal.
Should I use anti-seize on spark plugs?
Only if the manufacturer recommends it, and sparingly. Many modern plugs have coated threads and specify installing them dry.
What happens if I ignore worn spark plugs?
Misfires increase, fuel economy drops, and unburned fuel can overheat and damage the catalytic converter, turning a cheap job into an expensive one.