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Car & Auto Repair

Spark plug replacement cost calculator

Work out what replacing spark plugs will cost from the plugs and the labor. The plugs themselves are inexpensive; the labor swings with how easy they are to reach, from a quick job to hours on an engine where the intake has to come off. The calculator adds it up, and flags when a misfire is really a coil.

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Change anything. The answer updates as you type.

Usually one per cylinder: four for a four-cylinder, six for a V6, eight for a V8. Some engines have two per cylinder.
The plug itself. Standard copper plugs are cheap; iridium or platinum long-life plugs cost more but last far longer, and many engines require them.
Time to fit them. Plugs on top of the engine are quick; plugs on the back bank of a transverse V6, or under the intake manifold, take much longer.
The shop's hourly rate. Dealers charge more than independents.
A failed ignition coil or worn plug wires replaced at the same time. A misfire is often a coil, not just a plug. Zero if none needed.
Estimated cost
$168

Typical range $143 – $227

  • Spark plugs (count × price)$48
  • Labor (hours × rate)$120
  • Ignition coils or wires$0
  • Total$168
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$150 to $400 is a V6 or V8, or plugs that take real work to reach. Confirm whether a coil also needs doing.

What this assumes, and where it could be wrong

Every one of these is a place the number could be off. They are here because you should be able to check our working, not because we are hedging.

THE PLUGS ARE CHEAP; THE LABOR IS WHERE THE PRICE HIDES.
A set of spark plugs costs little, so the whole price of the job is really the labor, and that depends entirely on the engine. Plugs sitting on top of a four-cylinder are a quick job; the rear bank of a transverse V6 tucked against the firewall, or plugs under the intake manifold, can be hours of work to reach. The same set of plugs can be a cheap service or an expensive one purely because of access

Use the plug type the engine specifies, usually a long-life plug. Many modern engines call for iridium or platinum plugs that last a hundred thousand miles or more. They cost more than old copper plugs but last several times as long, and downgrading to cheap copper plugs in an engine designed for iridium means changing them far more often. Match the plug to the manual.

A misfire is often a coil, not just a plug. If the engine is running rough or a cylinder is misfiring, the ignition coil for that cylinder may have failed, and replacing plugs alone will not fix it. A quick diagnosis identifies which cylinder and whether it is the plug or the coil, so you do not pay for plugs and still have the misfire.

It is usually scheduled maintenance, so do it on the interval. Spark plugs wear slowly, and the manual gives a replacement interval in miles. Replacing them on schedule keeps the engine running smoothly and efficiently; waiting until they cause a misfire risks fouling and, occasionally, damage. The interval, not a symptom, is the cue on a well-running car.

The defaults are ours and are a starting point. The plugs, the labor, and any coils are yours, and the estimate turns almost entirely on how buried the plugs are and whether a coil also failed.

Frequently asked questions

How much does it cost to replace spark plugs?
It is mostly labor. The plugs are inexpensive, so the price depends on how easy they are to reach: a four-cylinder with plugs on top is a cheap, quick job, while a V6 with plugs against the firewall or under the intake manifold takes hours and costs much more. The calculator above adds it up. A failed ignition coil, if there is one, adds to it.
Why is a spark plug change so expensive on some cars?
Access. On many transverse V6 engines the rear bank of plugs is tucked against the firewall, and some engines route the plugs under the intake manifold, so reaching them means removing parts and hours of labor. The plugs themselves are cheap; it is the labor to get to them that makes the same job cheap on one car and expensive on another.
How often should spark plugs be replaced?
On the interval in your car's manual, which depends on the plug type. Long-life iridium and platinum plugs, which most modern engines use, commonly last a hundred thousand miles or more; older copper plugs far less. Replace them on schedule rather than waiting for a misfire, and use the plug type the engine specifies, not a cheaper downgrade.
Do I need to replace ignition coils with spark plugs?
Not always, but a rough-running engine or a misfire is often a failed coil rather than a plug. If you are replacing plugs because of a misfire, have the coil for that cylinder checked, because new plugs alone will not fix a bad coil and you would be back with the same problem. On a routine scheduled change with no misfire, the coils are usually left alone.

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