How Long Do Spark Plug Wires Last? (Guide)

Spark plug wires or cables ferry current to the spark plug. They are crucial components in a vehicle’s ignition system. Spark plug wires or ignition cables can last up to 80,000 miles. However, when damaged, they can cause problems for the engine. Misfires, engine surging, engine hesitation, hard starts, and many others are associated with faulty ignition cables.

What causes spark plug wires to wear quickly? The main cause of a reduced lifespan for spark plug cables is repeated overheating. Overheating in automobiles is due to the pre-ignition, and malfunctioning of the cooling system. Pre-ignition leads to heat build-up in the combustion chamber. That causes the spark plug to fail.

In this guide, I will help you to understand how long spark plug wires can last, and how to diagnose a faulty spark plug wire. Without a working spark plug wires, your engine will not be able to fire properly.

A standard spark plug wire can last up to about 60,000 to 70,000 miles. You should fetch a quality set of spark plug wires and replace the old existing ones before their failure. Do not wait for them to fail completely to avoid catalytic converter damage. A problem caused by a misfiring engine. Misfiring is one of the symptoms of worn-out spark plug wires. Changing the spark plug wires improves the engine’s performance in general.

How Often Should Spark Plug Wires Be Changed?

mechanic in blue glove checking the car's spark plug
Video | Scotty Kilmer

Replacing worn-out spark plug wires enhances the performance of the ignition system. On that note, it is, therefore, crucial to replace expired spark plug wires just before they wear out.

Some vehicles are equipped with extended-life spark plug wires. But that doesn’t guarantee that your spark wires won’t wear out. You should check your ignition cables every 30,000 miles. You can also check other components that might require replacement such as filters (air and fuel filters) and brakes while checking the spark plugs.

Frequent spark plug wires and other inspections will help you to maintain your car’s good condition. If you are an automotive engineer, you track the cause of a car’s problem easily and notify the owner of repairs. Constant repairs uphold the value and reliability of a vehicle. Developing issues can also be traced and their progress halted.

How Many Miles Do Spark Plug Wires Last?

A straightforward answer will be, 60,000 to 70,000 miles. However, that is dependent on many factors. Worn-out rubber boots at the ignition wires’ terminal can prompt their replacement. Damaged rubber boots hinder the good connection of the cables to the spark plug. You should get a new ignition cable to ensure the safety of your engine, and vehicle in general.

Why is my ignition cable getting worse with time? Well, they are bound to deteriorate with time because of friction and the heat generated by the car’s engine.

How Do I Know If My Ignition Cables (Spark Plug Wires) are Bad?

car engine in zoom

Not knowing when your spark plug wires are damaged or worn out can be catastrophic. The ignition cables play major roles in a car’s electrical system – the ignition system to be specific. I have compiled several detailed symptoms of lousy ignition caused by damaged spark plug wires. If you notice any of these issues, your spark plug wires are probably bad:

  1. Hard Starting. A defective ignition cable can cause this problem. However, the major causes of hard starting include corroded battery terminals, lousy injectors, lousy starters, and faulty ignition leads. Nonetheless, you should verify your ignition cables first before proceeding to analyze other potential causes.
  2. A misfiring engine. Engine misfiring is annoying. It is caused by erratic (incomplete combustion) and, irrespective of your car’s model and “age”, engine misfiring is bound to happen. The analytical examination of engine misfiring shows that faulty spark plug cables are the cause. The spark plugs, due to a faulty cable, fail to transmit the correct spark density from the distributor.
  3. Engine Delay. If the ignition wire develops cracks, it will transmit turbulent or irregular electrical spark to the spark plugs. That is caused by electrical misconduct during the spark transmission from the ignition coil to the spark plug. The electrical misconduct leads to engine hesitation or delay as the gas moves to the engine.
  4. Engine surging. The engine is another indicator of a bad ignition cable. This usually happens when there the insulation coating of the ignition leads or cables sustains electrical leaks. The leaks will cause the electrical current to experience spurts or even stop transmitting the spark to the spark plug. Eventually, the engine will experience surging problems.
  5. Rough idling. This is a common engine issue triggered by many factors, including bad spark plug wires. You can determine the overall status of the engine by examining how it runs when idle. However, you should be aware that engine idling is mainly caused by the spark plug itself rather than the wires. In that case, you should first verify the status of the plugs before you proceed on to check the ignition cables.
  6. Reduced engine power. Spark plug wires should convey uninterrupted electrical sparks. Any deterioration of the spark destabilizes the spark, eventually, weak sparks ignite the fuel. The combustion process is affected and the overall power out of the engine declines. (1)
  7. Finally, check the dashboard-light notification. The ECU signal on the dashboard shows the status of your engine. If you get the light pop-ups on your dashboard, the spark plug cables may be the issue, check them out.

Does Changing the Spark Plug Wires Improve the Performance?

Frankly, yes, swapping the spark plug wires will enhance the overall performance of your vehicle. However, you need to replace the old ignition wires with the correct and undamaged spark plug wires.

Brand ignition cables enable the engine to function optimally. The efficiency of the engine is also improved. (2)

Follow the following guidelines to choose the correct spark plug wire for your car model:

  • Select ignition cables that can withstand the heat and stress in your engine system
  • The new ignition cables should realize the piston-to-plug clearance accordingly
  • They should remove the engine’s heat efficiently
  • They should provide enough spark to light the air or fuel mixture.

Take a look at some of our related articles below.

(1) combustion process –
(2) efficiency of the engine –

Video References

Scotty Kilmer

Way of the Wrench

How helpful was this article?

Were Sorry This Was Not Helpful!

Let us improve this post!

Please Tell Us How We Can Improve This Article.

About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

| Reach Me