We Buy All Cars, Running or Not!

9 Signs of Bad Spark Plugs: All You Need To Know!

Signs of Bad Spark Plugs

Here are the 9 most common signs of bad spark plugs:

Auto Repairs Are EXPENSIVE

  1.  Engine misfiring
  2. Reduction in fuel economy
  3. Problems with acceleration
  4. Issues with starting the vehicle
  5. Troubles with rough idling
  6. Problems with compression leaks
  7. Check engine light Illuminating
  8. Mileage issues
  9. Troubles with the heat range

The spark plugs are minor components in your vehicle; however, they play a significant role in how your combustion system operates. 

Any problem with these spark plugs might prevent your vehicle from creating the required energy, and that's where you'll deal with some consequences that might be minor in the beginning but can easily build up.

It is critical for drivers to maintain the spark plugs all the time. However, these spark plugs are not designed to last forever, and they will be a point where you have to fix them or replace them.

Familiarizing yourself with the most common signs of bad spark plugs is one of the easiest and most important things you have to start with. There are plenty of things that could go wrong when the spark plugs are not operating properly. However, there are some signs that you'll notice more than others, and they should immediately bring your attention to the issue with the spark plug.

Whenever you noticed any of the signs of a bad spark plug, you'll have to immediately replace the spark plug or at least have your mechanic perform a thorough inspection.

This article highlights 9 signs of bad spark plugs that you will notice anytime the spark plug goes bad.

Tips for changing spark plugs

 What is the spark plug And what does it do?

Before we dive into the details about the signs of bad spark plugs, we must familiarize ourselves with the purpose of the spark plugs in our vehicle. 

In any vehicle equipped with a combustion engine, certain things have to operate simultaneously for your vehicle to generate the right energy level. The engine must receive the right amount of fuel and air. Having the right amount of fuel and air is not enough if you don't get the ignition spark at the right time with the right frequency, which is where the spark plug role comes in.

The spark plug produces a very small spark to ignite the air-fuel mixture. Imagine if the spark plug is not working properly; what could happen? You won't have any energy produced, and therefore, if all the spark plugs are not working properly, you won't be able even to move your vehicle.

How To Remove The Car Battery

9 Signs of bad spark plugs

Now you have a good understanding of what could go wrong when the spark plugs don't operate properly, let's take a closer look at the nine signs of bad spark plugs that automotive experts put together:

  • Engine misfiring

The first and most immediate problem that you'll deal with when spark plugs don't operate properly is engine misfiring. If you're not familiar with engine misfiring, it is a situation that could happen when one of the different elements involved in the combustion process not to operate properly. 

For example, if the engine does not receive the right amount of air and fuel, you will deal with engine misfiring. Similarly, if the spark plug does not produce the right spark at the right time, you will also deal with engine misfiring.

Unfortunately, you cannot immediately say that you're dealing with a bad spark plug by just noticing engine misfiring. Instead, you are mechanic needs to perform a thorough inspection to confirm the real culprits and let you know whether it's related to the spark plug or not.

  •  Reduction in fuel economy

Another very common consequence of a bad spark plug is a reduction in fuel economy. Remember that the combustion system operates very precisely, and if the spark did not get generated immediately at the right time, the engine will consume more fuel than it should, and that's where you'll notice a reduction in fuel economy.

As an average driver, you might not understand exactly why or how the reduction in fuel economy happens. However, you'll notice that you'll have to visit the gas station more frequently than before. When this happens, you must consult your mechanic to check what's going on and confirm whether it's an issue related to a bad spark plug or not.

If you are mechanic confirmed that the spark plug is the root culprit, you will need to get it replaced as soon as possible before things get more complicated and repair costs build up.

  •  Problems with acceleration

Of course, if your engine cannot produce the right amount of energy at the right time, you will have difficulty accelerating your car. This is because whenever you hit the gas pedal trying to ask for more energy fuel engine will try more and will be very stressed to generate the energy that's needed; however, it will not have support from the spark plug, and that's why you have difficulties accelerating.

Again, this difficulty in acceleration can be related to other stuff. Therefore, you cannot immediately replace the spark plugs just because you suspected an issue with them. 

Your mechanic should have the required tools to help him figure out the issues related to a bad spark plug or a combination of multiple culprits.

types of spark plugs

  •  Issues with starting the vehicle

The spark plugs are not typically involved in starting your car, but you'll have difficulty starting your vehicle if there is a problem with a spark plug. Yes, the battery, and the other components of the starting system are responsible for turning on your vehicle. 

However, if you want to get your vehicle moving a single inch, you'll need involvement from the combustion system, and if all the spark plugs are not operating properly, you might not be able to move your vehicle, and you'll have difficulty starting it.

  •  Troubles with rough idling

The longer you own your car, the more you'll notice when it's not behaving properly. For example, if you realize that your engine is having trouble whenever you try to idle, it could indicate an internal issue. 

Rough idling is not a normal thing, and whenever you feel bad your engine is stressing every time you're an idol, you have to take the issue seriously and consult your mechanic. 

Rough idling is one of those situations where you cannot confirm immediately that it's something related to a bad spark plug, but it could be.

  •  problems with compression leaks

Performing a visual inspection helps you confirm whether you have a problem with a spark plug or not. 

For example, if you look at the spark plugs and remove them from their location, you might notice some brown discoloration on the ceramic component connected to the spark plug. This is not a good situation, and this is not a good sign. Therefore, you should immediately replace the spark plugs whenever you notice this issue.

Keep in mind that is performing this inspection requires a certain level of mechanical skill sets. Not every driver can do this, and if you have the skills, you are encouraged to do that; otherwise, leave it to professionals. 

What Does A Spark Plug Misfire Feel Like

  •  Check engine light Illuminating

Another symptom indicating that you're dealing with a bad spark plug is when the check engine light illuminates. Keep in mind that the check engine light illuminates for various reasons and a bad spark plug is just one of them.

 To confirm if your issue is related to a bad spark plug, you can use a tool like the OBD scanner. This scanner scans the internal errors in your computer and translates them into a form of an error code.

Depending on your scanner's complexity, you might get additional information translating the meaning of this error code. However, if you don't have such a scanner, you can easily Google the error code on the internet and see what it means.

Once you confirm that your problem is related to a bad spark plug, you'll have to replace it immediately. Your mechanic should provide you with additional recommendations about the number of bad spark plugs and other details you'll need before fixing your car's problem. 

  •  Mileage issues

While automotive experts focus on monitoring the signs of a bad spark plug, you can also be proactive about the problem and replace the spark plugs before they get worse.

For example, they are expected to last about two and a half years or probably close to 30000 Mi. That's why when you feel that your car is approaching the threshold, it is recommended that you inspect and replace the spark plugs even if they're not going bad yet. This way, you don't have to deal with any of the symptoms of a bad spark plug that could result in other more complicated consequences that could cost you thousands of dollars On repair.

  •  Troubles with the heat range 

Finally, the spark plugs should be installed in a certain way by leaving a specific distance between the spark plug itself and the other components around them.

Therefore, even if you recently replaced the spark plug, you might immediately deal with some issues indicating that the spark plugs are still not in good shape. This happens if you hired an inexperienced mechanic to perform the job, or you would have placed your spark plugs and did not follow the good recommendations regarding the heat range.

Thus, it is critical that you consult an experienced mechanic and never attempt to replace your own spark plugs if you don't have the right level of experience.

How to clean a spark plug

How much does it cost to replace the spark plugs?

Replacement cost depends heavily on the quality of the spark plug and the number of failed spark plugs. Typically, spark plug replacement cost ranges from $66 to $250. There are plenty of high quality spark plugs that might be a little bit more expensive but you are worth it because they don't feel as frequent.

Keep in mind that labor cost is another important factor and spark plug replacement cost. Do you want a balance between where you get the job done and how precise you want your mechanics to be so your balance between the final deliverable quality and the amount of money paid. 

That's why even though dealerships hourly rate cost is much more expensive than small independent shops, there are plenty of luxury cars drivers who prefer to go to the dealership to confirm that the job is done properly and prevent any potential mistakes.

Note that it's not recommended to replace your own spark plugs unless you have the right level of experience. This is because many of the DIYs might not work the first time and introducing a simple mistake in the engine compartment can lead to significant repair costs. 

Spark Plug Replacement Cost


The spark plugs are critical components in your combustion system. Over time of use, these components are expected to fail. When that happens, you'll have to replace that immediately to continue driving your car properly and prevent more complicated consequences.

This article highlighted nine signs of bad spark plugs to watch for. Once you notice any of these signs, you must replace the spark plugs immediately. Keep in mind that some of these signs might be related to other culprits, and that's why your mechanic needs to confirm the root problem before replacing the spark plugs.

In some scenarios, spark plugs might lead to significant problems that are triggered before you detect facial and that's where you have to pay thousands of dollars on repair. 

When this happens, it is important that you evaluate the situation carefully before spending too much money on a vehicle that's not worth it. Thus, don't be surprised to deal with situations where you have to sell your car instead of fixing it. 

Cash Cars Buyer is one of the top-rated car removal companies in the nation that guarantees to pay you the top dollars and provide you with free towing despite your living location around the United States. 

Our process is very straightforward and doesn't take more than a couple of days to get your car removed safely and for the most money. 

All it takes you is to:

  • Describe your car’s type and condition
  • Receive our instant free quote
  • Accept the quote 
  • Get your car removed and receive your cash payment on the spot!

To learn more about our process and our teen, you can reach out to us by giving us a call at 866-924-4608 or visit our home page click on the free instant online offer.

© 2022 Cash Cars Buyer. All Rights Reserved. Terms & Conditions | Privacy Policy | Sitemap