The Shocking Truth: Top Causes of Spark Plug Failure

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The Spark plugs are the crucial components of an engine that generate electricity to ignite the fuel-air mixture inside the vehicle for producing energy. By putting the engine’s pistons in motion, your car can power up, stay powered up, and produce a smooth burn of the compressed air-fuel mixture. Some engines need more than a spark plug.

For instance- several Mercedes-Benz engines have two spark plugs per cylinder. In some circumstances, the spark plugs of a car will fail even within its intended lifecycle.

Now, Spark plugs have a limited lifespan. As a result, it becomes malfunctioned. Moreover, there are also several reasons that lead spark plugs to go bad fast. Driving with bad spark plugs can lead your engine down. Some major  Causes that lead spark plugs to go bad fast.

What Causes Spark Plugs to Go Bad Fast

Spark plugs are a crucial part of your car engine. They’re responsible for igniting the fuel in the cylinder to create power, and they can be replaced as often as ever between 20,000 and 30,000 miles or so. Unfortunately, spark plugs will eventually go bad- but why is that?

sign of bad spark plug

Bad Fuel Filters

Spark plugs can suddenly go bad not because anything is bothering them, bad fuel filters can be the main culprit behind it. It can cause the tip of the plug to get oily and dirty, resulting in buildup and damage to the plug, which will ultimately cause it to fail. If you have an older vehicle and you know it’s burning oil, then the lifespan of your spark plugs will most likely be shorter than usual.

Unsuitable Spark Plugs Gap

There’s a small gap between the metals on the tip. It has to be accurately measured for your engine when the spark plug is installed. if the gap is incorrect there will be extra stress that can happen on the tip and that leads to wear out faster. It can be the ghost that causes spark plugs to go bad faster.

Leaky Head Gasket

Coolant leaks into the combustion chamber can cause spark plug fouling. This is really bad news because a leaky head gasket can be very expensive to repair. A fouled spark plug may be an early sign that a head gasket is starting to leak.


If your engine’s cooling system doesn’t function at peak performance it tends to engine run hot. This can be also a major reason for fouling spark plugs. Overheating of the tip of the spark plug can cause it to wear out prematurely.

This can arise from a number of different causes. If the timing of the engine is off and pre-ignition occurs, this can cause excess heat to build up in the combustion chamber.

Wet Spark Plugs

A slow steady flow of oil into the combustion chamber is one of the leading causes of spark plug problems. It can cause the tip of the plug to get oily and dirty, resulting in buildup and damage to the plug, When the spark plugs are covered with unburned gasoline it allows not firing.

Wet-fouled spark plugs can be caused by flooding the engine when attempting to start a cold engine. It can make a short circuit to the ground instead of jumping across the electrode gap

Carbon Buildup

Carbon fouling is one of the potential fouling problems that happens to spark plugs.

There are several reasons behind it. We are going to focus on some majors.

  • Star and stop rapidly– where a vehicle is stopping constantly, is never good for the vehicle. It not only lowers vehicle gas mileage, but it can result in carbon fouling of the spark plugs. 
  • Vehicle Idling– When a vehicle does not drive for an extended time period, the spark plugs do not get hot and that means they cannot burn off the carbon or fuel deposits. A vehicle left idling for a long period of time will often end up with carbon fouling.

Rich Fuel Mixture

A rich fuel mixture can result in carbon fouling. There are several potential reasons the fuel mixture is rich and these reasons range from a leaky fuel injector to problems with vehicle oxygen or coolant sensors.

How to Stop Spark Plugs From Turning Black

Spark plugs need to be cleaned and maintained on a regular basis. If they are not, the plugs will eventually turn black. We’ll discuss some tips on how to stop the plugs from turning black.

  • Regular maintenance is essential to keep your car running smoothly. For example, you should do a spark plug clean with some paper towels so that all of the dirt and oil are removed from it before driving off again.
  • After you’ve been running the engine for a longer time, it’s important to take off your spark plug and use a hard brush or piece of steel wool on both ends with light oil. This will not only clean out black residue from the inside but also help performance by making sure all surfaces have an even coating in order for combustion to happen properly.

Related: What Happen If Spark Plug wires on wrong?

Sign of Bad Spark Plug

bad spark plug sign

Now, we will look through signs that indicate bad spark plugs. It’s important that if you’ve got any of the following symptoms you rule out the spark plugs first by taking them out and examining them. Spark plugs are usually cheaper to replace than other engine parts, so even if they look okay, it might not be a bad idea to change them anyway.

Poor Fuel Economy

A very common symptom of bad spark plugs is a noticeable drop in fuel economy. Do you stop at the gas station more than your expectations? If suddenly mileage falls down the spark plug can be guilty of it. Either your spark plug does not function properly or it has gone bad.

Engine Back Firing

This symptom is really associated with an unbalanced air-to-fuel ratio. This can vary from engine to engine, yes it is still possible.

Hard to Start

While you can start your engine like before you did, your first thought may be a dead battery or empty tank. Yet a bad spark plug can be the cause, that will leave you mad. You won’t be going anywhere if your spark plugs can’t produce the spark to start.

Engine Misfires

An engine misfire results in the engine stopping for a moment and then regaining its normal operation. This is most recognizable when accelerating or when the car is idle. This means the engine is not functioning as smoothly as it should because one or more spark plugs are not firing properly. However, unless the spark plugs are replaced the new converter could soon fail.

Lack of Acceleration

The lack of proper acceleration is another sign of faulty spark plugs in a car. if your vehicle has lost its get-up-and-go, bad spark plugs could be the culprit. During this time your engine will run at a low RPM. Typically you will also feel a vibration throughout the vehicle. Ignoring this symptom can lead to serious and costly damage to your vehicle’s engine.

Rough Idle

The car engine will run at a lower RPM during idling and run smoothly without any noticeable vibrations or sound. When your spark plugs are performing as they should, your engine sounds smooth and steady. Failing spark plugs can result in the engine becoming rougher.


Why do my spark plugs keep burning out?

The reason your spark plugs are burning out so often is that they’re covered in gas or fuel. When this happens, it causes a leak which then makes those precious little sparks go flying off at the slightest touch.

What happens if you drive with a bad spark plug?

If you’re driving and have a bad spark plug, then your engine might not work properly. This can cause problems such as misfires or hard starts when trying to accelerate quickly from stoplights, all signs that something is wrong.

Can spark plugs suddenly go bad?

Yes, Spark plugs sometimes go bad suddenly, but there is no way to know when they will fail. They wear down and occasionally misfire or don’t work at all a lot like the human body.

What kills a spark plug?

If the tip temperature is higher than 850°C, it may lead to overheating and blisters on the ceramic around the center electrode. This can cause meltdowns with subsequent pre-ignition/detonation which will damage your engine for sure.

Can bad spark plugs cause rattle?

Older cars with high mileage may have faulty sparks due to corrosion. This causes a rattling sound you’ll notice while driving and accelerating, among other things

Final Thought

Spark plug problems can arise from various things. No matter if they are continuously in use when the engine is in use. we focused on some major causes that make spark plugs go bad very quickly.

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