Can Spark Plugs Go Bad from Sitting?

A spark plug is an important part of a vehicle to produce the vehicle’s engine power. It supplies air/fuel mixture and creates pressure within the vehicle engine to enable it to run. Yet a common query remains among users, Can spark plugs go bad from sitting?

The answer is no! Your vehicle spark plug will never go bad even when sitting for a long while. However, it might get bad if it gets affected by water ingress. Also, if the spark plug gets corroded in its cylinders, it might be the reason for your worries.

Each of the spark plugs is designed with a ceramic insulator which saves them when they get older. So, until the electrodes of the spark plugs are corroded, it won’t go bad even when sitting for years.

Spark Plug Function In A Car

A spark plug is like a device in a car engine situated on the cylinder head that works like a lightning bolt. It creates a spark that helps the fuel to ignite in the fuel pump or in the gas tank. That’s how the engine powers up and runs.

Spark plugs use electrical signals to produce sparks. The electrical signals go from the battery to the ignition coil through a spark plug wire and create the sparks. These sparks assist in igniting the air and fuel mixture in every cylinder. 

These simple plugs produce the arc of electricity in terms of two leads and these leads aren’t touched with one another but close enough. As a result, electricity can bridge the gap without interruption between them.  

Can Spark Plugs Go Bad from Sitting

Can Spark Plugs Go Bad from Sitting

As mentioned earlier, spark plug problem doesn’t occur due to sitting. A spark plug generally comes with a long-lasting life span that enables it to sit inside the vehicle for several years without having any issues. The three best reasons why the spark plugs don’t get bad from sitting are-

● Robust Body Construction

The spark plug is designed with robust body constructions that help protect from unwanted external effects.

The body parts of a spark plug are well designed to provide protection from rots. Because the spark plug is placed inside the cylinders thus it never comes with any direct physical contact. The spark plug hole on the cylinder head protects a spark plug from any sort of combustion pressure.

Since a spark plug construction includes firm materials like ceramics, copper, platinum, and porcelain it can be considered a device that’ll not be easily damaged by any pressure from outside.

● Easy Storing Process

Another reason is an easy storing process. Storing the spark plug requires no hassling systems. If you can store the spark plug in good condition, it will also come with great longevity.


● Designed to be Fit While Not in Use

Spark plugs aren’t designed to be in use all the time. If you don’t use your spark plug for a long time, it won’t go out of order unless they have lots of unexpected moisture in their body. So generally, it won’t get affected from a long time sitting.

How Long Does A Vehicle Spark Plug Last

The longevity of a spark plug differs from the quality, brand, and model. Usually, the average durability of a spark plug varies between 30000 to 80000 miles. However, it can go up to 1,00,000 miles based on condition. 

If you use ordinary spark plugs, for instance, nickel or copper, they should be replaced after each of your 50000 (maximum)  miles running. But, it can be a bit more if the manufacturers recommend it.

High-quality spark plugs, for example, platinum or iridium don’t require any replacement before you run your car up to 150000 miles maximum.

So, how long do spark plugs last completely depends on which quality spark plug you have. The durability can be more or less.

What Affects Spark Plugs if Nothing in The Engine Hit Them?

Usually, there are a lot of things to consider when it comes to failing spark plugs. So, when the spark plug goes bad, it is not solely because of anything in the engine hitting them, rather the potential reasons can be anything like:

  • The produced pressures keep fluctuating inside the cylinders explode to the temperature and pressure
  • The functionality of the faulty spark plug comes with tremendous vibration at a high RPM which badly affects the spark plug’s structural integrity
  • Temperature vibration that happens between storks causes damage to the tip/electrode parts
  • A tendency to contract and expand results in stress and damage to the spark plug’s internal structure
  • On the way in and out, spark plug electrodes are hit by the electrons. Thus, each spark plug dislodges one or two molecules over time causing severe damage and making a bad spark plug
  • The worn-out electrodes cause a short circuit that prevents your vehicle spark plug from igniting
  • The temperature of the combustion chamber is reduced when the engine compression is reduced. This situation creates an oil fouling problem. As a result, the spark plug becomes hotter and takes more time to ignite

What Causes Spark Plug Not Working (what causes spark plugs to go bad)

Usually, the vehicle spark plug goes bad for several reasons and the most frequent ones are-

●  Exceed the Recommended Distance

One of the top reasons is the distance your vehicle covers. You must maintain the distance recommended by the manufacturer.

Because all the spark plugs are recommended to replace after a certain mileage. If you don’t follow the manufacturer’s recommendation over the period of time, your vehicle spark plug will go bad no matter whether it’s sitting for a long time.

● Defective Engine Parts

If your spark plug goes bad, it won’t go bad from sitting. Rather, you must consider the other defective parts of your vehicle that might affect the spark plug’s efficiency and performance.

And, these parts are, for instance, malfunctioning catalytic converters, clogged air filters, oil contamination, or overheating things. So, if your spark plug loses its performance, you must focus on the mentioned areas and fix them.

● Oil Leaking

Another important reason is the oil leaking issue. If oil leaks into the combustion chamber, it will surely damage the spark plug. This can happen with the oily spark plug. Oil leaking makes the spark plug oily and dirty which interrupts in longer life span.

● Overheating

Wrong ignition system or timing and also the pre-ignition cause overheating to the spark plug electrodes. And, if the spark plug electrodes get continuously overheated, they will wear out prematurely.

●  Improper Spark Plug Gap

To ensure the proper arching occurrence at accurate voltage, the spark plug should come with the proper gap between its electrodes and the center at the tip. If you cannot fix the gap accurately, it will create additional stress in the spark plug tip. As a result, the spark plug will lose its performance. 

How Do You Know if The Spark Plug Is Not Functioning(spark plug failure symptoms)

Many of the signs are there that come into consideration to determine whether or not your vehicle spark plug is functioning. Considering all of them, 3 are the top ways to understand why the spark plug isn’t working-

1. Misfires

If the air and fuel mixture is damaged, it will create an engine misfire in the spark plug. It can happen if the air and fuel mixture starts igniting late or earlier than it should. Also, if it doesn’t ignite, it will create a misfire. And, misfiring means the spark plug isn’t working.

2. Loud Idle

If your car comes with a loud and vibrant idle, you must know the spark plug is not functioning properly. This occurs due to the unburned fuels that come from misfiring.

3. Tough Engine Start

If you notice that starting your engine seems difficult, it may caused by the faulty spark plug. So, you need to check out whether the spark plug is working. At maximum times, a damaged spark plug makes it tough to start the vehicle engine.

What is the average cost of spark plug replacement?

The replacement cost of a spark plug will remain within $10. However, if you cannot replace it yourself and need professional assistance, you’ll have to spend up to $200.

How to Choose the right type of spark plug for my vehicle?

Well, there are different types of spark plugs, for instance, single/double platinum, copper, iridium, and silver. Not all the types are for all vehicles. So, check out the vehicle’s manual to get the right type of spark plug that fits your car the best.

Do spark plugs go bad in lawnmowers?

Spark plugs get excessive deposits built while creating sparks during your lawn cutting time. So, it gets dirty and loses the efficiency to ignite fuel. Therefore, it’s always suggested to replace a spark plug each year.


No spark plug is manufactured to burn down their electrodes while sitting. So, there’s no reason to be concerned about “Can spark plugs go bad from sitting?” If a spark plug goes bad, there can be some other issues to consider.

Since the spark plugs are a significant part of the internal combustion engine, you must take proper care of them. Without the spark plugs, no fuel ignition will happen in the combustion chamber.

Leave a Comment