Q: When Should Spark Plug Wires Be Replaced?

asked by on November 19, 2015

When should spark plug wires be replaced?

Tune-up $182.97 - $912.45 Get a Quote
Spark Plugs Replacement $98.11 - $638.97 Get a Quote

When deciding to replace your spark plug wires, you should first check your owner’s manual. Follow the recommended maintenance schedule that the vehicle manufacturer has published.

Besides regular maintenance, another reason to change your plug wires is due to failure, which can happen at any time.

Some causes of spark plug wire failure include:

  • Coming into contact with motor oil which deteriorates the plug boot and wire insulation.

  • Spark plug wires chafing against a bracket which allows the spark to jump straight to the engine block and bypass the combustion chamber inside the engine altogether.

  • Poor contact due to corrosion inside of the plug wire connections.

Symptoms of plug wire failure can include poor idle quality, lack of power, engine misfire, emissions test failure, or decreased fuel economy.

An old mechanic rule of thumb was to replace the plug wires with every major tune-up, which included spark plugs, distributor cap and rotor, and points and condenser. Nowadays, that rule of thumb is largely ignored because of more advanced systems, better materials, and higher quality production values.

If any of these issues are familiar to you and you think your vehicle may need to be checked out, have a qualified mechanic inspect and replace your faulty spark plugs as necessary. A healthy car is a happy car.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

What others are asking

new stereo unit not working, interior lights and fuel level not working or showing up

Following the colors of the wires is not a full proof method to be sure you have made the correct connections. You clearly have some connections that are not correct. The only way to figure out what is what in...

Wipers don't turn off on 1995 Volvo 960

Hello. This is a problem with the wiper module. The module fails internally and causes the wipers to continue to stay on. I always check for power at the module first to see if it is getting the on signal....

Hello, have 2001 Monte Carlo. Turn signals don't work. Replaced the turn signal switch and the hazard warning turn signal flasher. Still nothing.

Hi there. Check the lights fuses in the fuse box. If the fuses are good, then turn on the ignition key and check for power to the ignition switch on the fuse box. If there is power to the ignition...

Shaking of 2002 Hyundai Elantra

Engine shakes a lot of times because either the engine or transmission mounts are worn, or they are not running correctly. First thing you want to do is--have that motor mounts and the transmission mounts checked. It's old enough, 14...

Rough to no acceleration and misfire

It is possible that one or more of your spark plugs or ignition coils have failed. The spark plugs and the ignition coils make up the ignition system and this system is responsible for burning the fuel. If the fuel...

Car won't turn off; can't get key out of ignition

If your car is not turning off, and you are unable to remove the key, that may be sign that the ignition lock, or possibly switch, has gone bad. A failed ignition lock or switch can sometimes fail, and jam...

All of a sudden, all of my dashboard lights came on and loss power to my window and all gauges. The truck says it's in reveres the whole time.

Hello. The first thing to check of course is for blown fuses. Given the sudden nature of the failure, check for cut or damaged instrument panel wiring that might have shorted out as well, especially a ground wire. Instrument cluster...

Key does not turn and steering wheel locked.

The first thing I would recommend is to try turning the wheel and the key at the same time. Sometimes it is possible for the steering lock to bind the ignition cylinder. Turning the wheel away from the lock can...

Alternator not grounding on 2000 BMW 323Ci

Hello. If this occurred right after the accident, then I would check the ground connections on the battery first. If they are fine, then the wire going from the battery to the alternator needs to have a voltage drop test...

Related articles

How Can the Light Bulb Wiring Become Damaged?
Your Your car is as much electrical as it is mechanical. Wiring harnesses snake their way around the engine bay, and throughout the cabin of the vehicle. Most of your accessories run on electricity, and even the engine needs a...
How Can the Light Bulb Wiring Become Damaged?
Your Your car is as much electrical as it is mechanical. Wiring harnesses snake their way around the engine bay, and throughout the cabin of the vehicle. Most of your accessories run on electricity, and even the engine needs a...
How to Tell If Your Car Switches Are Dying
Since Since every part of your car is controlled or operated by a switch in some fashion, it is to be expected that the switch will eventually fail. Some of the most commonly used switches in your car are: ...