How Long Do Spark Plug Wires Last?

Did you know that spark plug wires are not made of actual wires? They are actually made of delicate carbon fibers which can break and separate over time.

It causes high electrical resistance that can eventually lessen the spark. Soon enough, it will result in misfires, poor combustion, or lousy gas mileage.

You don’t want to fall into much more trouble caused by a spark plug wire failure and severe performance problems. In this article, you will know the answer to “how long do spark plug wires last?” So, keep reading to learn more.

What Is a Spark Plug Wire?

The spark ignition system’s components that transfer high voltage pulses to the voltage source are spark plug wires.

It consists of a coil wire connecting an ignition coil to a distributor. These also have high tension leads, the plug, and coil wires. Both have connectors enclosed in an insulating material with insulating boots on ends.


Have you tried identifying what specific spark plug wire you are running? Going beneath the skin of a wire to discover its core component is the only method to properly identify one type of wire from another.

The most common varieties of ignition wires are the following.

  • Solid-core
  • Carbon-suppression
  • Spiral-wound

It’s important to understand the differences between wire types and ignition systems. However, when it comes to the higher end of the performance range, always refer to the manufacturer’s recommendations, particularly the ohm resistance.


The spark plugs are usually located on top of the cylinder head. Meanwhile, the piston goes down the cylinder, absorbing a mixture of air and fuel. The piston returns to the spark plug and compresses the mixture.

Generally, spark plug wires comprise a few core parts.

  • Central conductor
  • One or more layers of insulation
  • External sheath
  • Spark plug, coil, or magneto terminal
  • Distributor terminal
  • Insulating terminal boots
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An ignition coil sends the voltage to the spark plug when the piston is at the top dead center, generating a spark and sparking the air/fuel mixture.

Working Principle

Because they are meant to carry high voltage pulses between the coil or magneto and the spark plugs, spark plug wires are commonly referred to as high tension leads.

This is a typical usage of the term that you may be familiar with, the word “tension” relates to voltage rather than the more usual definition of the term.

Spark plugs and wires are designed to handle the high voltages produced by magnets and coils to:

  1. Help high-voltage pulses must be transferred without being damaged.
  2. Continue to be electrically insulated from the ground.
  3. Keep high temperatures seen in engine compartments from harming it.

How Long Do Spark Plug Wires Last

It will help if you change your spark plug wires before they wear out. It is recommended to change wires when you change your spark plugs (typically between 60,000 and 100,000 miles, depending on your owner’s handbook).

Benefits of Changing Spark Plug Wires

Spark plug wires, like spark plugs, distributor caps, and distributor rotors, are worn items. Meaning they will gradually wear down and need to be replaced at some point.

On the other hand, Spark plug wires often survive far longer than distributor caps and rotors, and some can even outlast extended-life spark plugs (i.e., plugs that use precious metals like platinum to reduce wear.)

Some benefits of changing your spark plug wires are:

  • The combustion process functions optimally
  • Improved vehicle performance
  • Improved fuel economy
  • The engine starts smoother and easier
  • Reduced harmful emissions

Remove Old Ones

Clean the area around your spark plugs thoroughly. You will have an open hole directly into the inside of your engine once you remove the spark plug.

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Any dirt or debris around the spark plug might fall right in, causing major wear or damage to your engine – something you should avoid for obvious reasons.

It’s time to start the actual process after you’ve cleared the region surrounding each spark plug of any oil, dirt, or other debris.

Install New Spark Plug Wires

To comfortably attach the tool to the spark plug, add the necessary combination of extensions and swivels to the spark-plug socket. Turn the spark plug in the other direction until it comes loose.

Even if you thoroughly cleaned the area around the spark plug before starting, be careful not to knock any previously unnoticed dirt into the now-open hole in the interior of your engine.


After double-checking the gap, carefully slide the plug into the open hole by hand. If your spark plug isn’t pre-treated with anti-seize, a little drop of anti-seize lubricant can be rubbed over the thread to prevent it from locking up due to heat.

Starting with a clockwise spin, gently screw the plugin, ensuring the threads are securely matched.

Frequently Asked Questions

What happens if you don’t change your spark plug wires?

When spark plug wires fail, one or more cylinders stop working, resulting in a rough condition. The electrical current running through the wire may short to the ground if the insulation abrades or a carbon track develops in one of the boots.

Additionally, when the engine is running, this may result in a visible spark seen with the naked eye and a harsh popping or cracking sound. You could get a shock if you handle a wire that has been damaged in this way.

What can cause damage to spark plug wires?

The following factors can harm a spark plug wire:

  1. Engine vibration can cause the electrical contacts at the spark plugs to loosen. The ignition coil and spark plug wires may be damaged if the spark plugs require greater voltage to ignite.
  2. High engine heat can cause wire insulation to burn, causing the voltage to jump to the ground instead of reaching the spark plugs.
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Are thicker spark plug wires better?

The difference between factory and aftermarket wires, which are occasionally thicker, is small for the average person.

Logic suggests that if a thicker wire makes a difference in your home’s walls, it must also make a difference in automobiles.

However, because of the thicker wire’s higher cost, it’s believed that the typical individual should not waste their money.

Are there any precautions when installing new spark plug wires?

Spark plug wires must be changed regularly to maintain a vehicle’s engine running smoothly.

Starting with the longest wire, remove and replace one wire at a time. You won’t have to be concerned about making a wiring mistake if you do them one time.

When removing wires, twist or rotate the boot to release it from the spark plug or distributor cap. The connection may be broken if you jerk or tug on the wires. Make sure you’re only pulling on the boot and not the cable.

Is there a difference in performance between different spark plug wires?

In today’s world, there are two basic distributor-cap plug wire connections. The most common HEI-style distributor cap male connector and the older female socket where the male connector is connected to the plug wire.

It all boils down to a matter of quality. OE manufacturers often utilize cables with a resistance of 3,500 to 5,000 ohms per foot.

This is a unit of electrical resistance measurement. Performance wires will have a lower resistance per foot, such as 40 ohms per foot.

The engine will start easier and have a smoother idle due to the reduced resistance. With this lower-resistance rating, there is a slight performance boost.

What temperature rating do your spark plug wires have?

A spark plug’s heat rating measures how much heat it releases. The spark plug’s heat range is the temperature range in which the plug performs well thermally.

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Each NGK spark plug has a heat rating; lower numbers suggest a hotter variety, while higher numbers indicate a cooler type.

The spark plug’s temperature remains too low, causing deposits to form on the firing end; these deposits create an electrical leakage path, resulting in a loss in spark.

When the spark plug temperature goes too high, it causes irregular combustion (pre-ignition), which results in the melting of the spark plug electrode, which can create difficulties like piston seizure.

Should I put heat socks on the spark plug wire boots?

Yes, if you anticipate problems and have enough space for the sock to fit without contacting the cable or headers.

If the space next to the boot is too tight, the ideal approach is to dimple the tube to make more room. Mild dimples, especially those near the head, do not affect power.

What are the indicators of bad spark plug wires?

While most recent cars have ignition coils, spark plug cables are still used in some passenger cars and trucks.

The spark plug wires are made of a low-resistance, long-lasting substance that can withstand the extreme circumstances found beneath the hood and the ignition system’s high voltage.

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Knowing the signs and symptoms of faulty spark plug wires and how to test and replace them can save you a lot of time and money.

Spark plug wires are essential components of every vehicle’s electrical system. When they start to fail, you’ll notice several indications of faulty ignition leads that appear to alert you to the possibility that something is wrong.

Failure to identify and address the source of these warning signs on time may result in more serious issues. Take a look at some of the most common signs of bad ignition cables.

  • Hard starting
  • Engine misfire
  • Engine hesitation
  • Engine surging
  • Reduced engine power
  • Check engine light
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Is it simple to replace spark plug wires?

Replacing your spark plug wires is as simple as changing your car battery, but your engine will behave strangely if you do it incorrectly. Your car may not be able to leave the garage until the wires are properly repaired.

Can you change the spark plugs without replacing the wires?

High-tension wires are separate components transporting electrical current from the distributor to the spark plugs.

As a result, you can replace the spark plugs without modifying the wiring. It’s possible that changing the wires simultaneously as changing the spark plug is the best option. 

Takeaway: Spark Plug Wires

Assume your car’s engine displays two or more signs of faulty spark plug wires. In such a scenario, you’ll need to identify and replace any damaged ignition wires to prevent worsening problems.

If you’ve made it this far, we’ve answered your question, “how long do spark plug wires last?”

In a nutshell, replacing a spark plug wire is rather simple. If you’re not sure you can diagnose and replace the cables on your own, hire a professional mechanic to inspect and replace them.

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