Skip the auto shop - Our mechanics make house calls

Q: When Should Spark Plug Wires Be Replaced?

asked by on

When should spark plug wires be replaced?

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.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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

Get a quote

What others are asking

Q: Air conditioning on high caused radio turn off, gas gauge to empty,warning lights on

The most likely cause of this is a battery with a failed cell, alternator, battery cable or the AC compressor itself. If the charging system has a fault, it will not be able to support all of the car's systems,...

Q: I need to diabke anti theft I changed out steering colum ignition switch looked at all fuses

Anything can be bypassed, but it will take more time and money to bypass the security system than it will to replace it. This is a common request from many customers and I can say that the manufacturers do a...

Q: 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...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.