7 Common Symptoms Of a Bad Muffler & Ways To Fix Them

By December 25, 2022Muffler

Like any other part of the vehicle, the muffler is prone to get damaged, mainly because of the level of hot gases it handles. 

When a muffler gets damaged, it comes with different signs like check engine lights (CEL), noises, engine misfire and poorer fuel economy. 

Personally, I have had a bad muffler on my Honda Accord. The first sign I noticed was the change in sound. Then some other issues started, like the check engine light, engine misfiring, and rusted muffler parts. I had to get a new muffler to have the problem solved. 

In this article I will highlight the common symptoms of bad mufflers and discuss how you could go about fixing them. 

7 Common Symptoms Of Bad Mufflers

1. Much louder exhaust

One of the significant symptoms of a bad or leaking muffler is louder sounds from the exhaust. Unless you are using a high-performance muffler designed to make your engine loud, your exhaust is not meant to be loud.

The sound coming from a lousy muffler is usually a loud roaring sound that is quite uncomfortable to hear. One major cause of the change in the muffler sound is a hole in the muffler or other parts of the exhaust system. 

Once the muffler has been damaged in any way, it will be unable to dampen the exhaust waves coming from the engine. It means that the sound wave can escape to the surroundings causing alarming noise.   

2. Lower engine performance 

The way the engine and the vehicle are designed generally, all parts connected to the engine, including the exhaust system, must function correctly for the engine to work fine. 

When the muffler or any part of the exhaust system experiences any damage, including leaks, it affects how the engine breathes. The exhaust will slow down, causing a significant build-up of gases around the engine area. It will ultimately cause the engine to lose power and display other symptoms like rough idling, misfire, etc.  

3. Increased emission smell 

Once you smell nasty exhaust fumes in the vehicle, something must be wrong with the muffler. The exhaust system is designed to direct the exhaust fumes away from the vehicle when driving so that it does not get into the vehicle. 

It is why most vehicles have the tip of the exhaust pipe facing the extreme rear of the vehicle or the side of the vehicle. It ensures that the gases exit far away from the vehicle. 

When you start smelling the fume, it means that there is a leak in one of the parts of the exhaust system. You need the muffler checked immediately. 

4. Bad fuel economy 

Another sign that your muffler may be going wrong is that your vehicle will experience an increase in fuel consumption. One of the excellent qualities of the muffler is its ability to improve the engine’s level of fuel economy. 

A good muffler can improve the level of exhaust gas flow through the exhaust pipe. With the engine breathing fine, it promotes a better air-fuel mixture, leading to better fuel efficiency. 

Depending on the problem with the muffler, it could cause the exhaust flow to be more restricted, which could affect fuel economy.

5. Exhaust rust 

One major problem that a bad or leaking muffler comes with is that the affected part begins to rust. If there is a hole in the muffler, it gives way for a foreign element to enter into it. 

Once the muffler cools down after being used, elements like water, rain dew, snow, or more that cause rust could settle in the muffler. 

Unlike the outer parts of the muffler and exhaust pipes that can be continuously coated with anti-rust material, you cannot do the same inside the muffler. When these elements begin to enter the muffler, it is difficult to stop the rust from happening. 

Also Read: Exhaust Leak 101: Fixes, Costs & Can You Still Drive It?

6. Engine misfire 

As we know, the muffler has a level of influence on the vehicle’s fuel consumption. A restrictive muffler can affect the way the engine functions. If the muffler’s internal components get damaged, it could cause it to be too restrictive. 

When the exhaust system is too restrictive, it will affect the air-fuel ratio due to the building up of back pressure. When there is too much back pressure, the engine will misfire. 

7. Check the engine light 

An unfavorable change in the exhaust gas flow could cause the check engine light to get triggered, primarily when it results in increased back pressure.

If the muffler is damaged, the O2 sensor can quickly pick up the change in gas flow and immediately notify the PCM, which would trigger the check engine light. 

Will Bad Muffler Cause Engine Issues

A bad muffler will cause engine issues. Depending on the type of damage, the muffler could cause a restriction in the gas flow or, worse, stop airflow, which could cause damage to the engine. 

Damage to the muffler could either be internal or a leak that causes gases to escape. When the damage is internal, it causes a restriction in the gas flow. 

If the internal damage is severe, it could cause a total block in the gas flow of the exhaust system. 

In this case, the chambers or other components of the engine might have failed or collapsed due to many factors, like heat or rust, causing a blockage in the muffler. 

Once there is either an extreme restriction or a complete stop in the gas flow, the engine cannot breathe well anymore. There will be excess back pressure, and engine performance will drop drastically. 

The O2 sensor will detect the excess backpressure, and this will cause an increase in fuel injected into the engine, causing the engine to run rich. An engine that runs rich will begin to experience signs like engine misfiring, rough idling, and stalling, among others.

If the problem persists without you having it fixed, the engine parts will fail one after the other. The failing parts will eventually cause a failed engine which will cost even more to get fixed. 

Now you have to fix the engine and have the muffler changed. It is why you need to replace the muffler once it fails. 

Also Read:

How Much Does It Cost To Replace & Install Muffler

Depending on the type and brand of a muffler, it will cost between $100 to $300 to purchase and install a muffler.  

Many professional mechanics advise that when your muffler has a problem, you get it replaced rather than repaired. However, it is possible to get the muffler repaired. Some professionals specialize in fabricating mufflers and other exhaust parts. 

It is essential to know that there are different types of the muffler. It is best to categories mufflers into groups, which are the stock and performance muffler. 

Stock mufflers are the normal mufflers that come with a vehicle, and it is easy to find original parts when changing your muffler. They are quiet and deliver the same service as the muffler that came with your vehicle. 

Flowmaster muffler

Performance muffler

Performance mufflers bring something extra to the table when compared to stock mufflers. Performance mufflers are designed to improve your vehicle’s sound and gas flow. They usually come with a more exotic sound to your vehicle and are not necessarily loud. 

Although some can be loud, some types of performance mufflers focus on improving the gas flow of the vehicle rather than sounds. 

Performance mufflers will cost more to get when compared to stock mufflers. Stock mufflers may cost between $50 to about $150. On the other hand, a performance muffler can cost from $100 to as much as $1,000. The price depends on the brand, the vehicle, and many other factors. 

You also need to consider the cost of labor when changing the muffler, that is, if you will not be doing the change yourself. The cost of getting a professional to help change the muffler usually starts from $100 and can go higher than that.  

Also Read:

Can You Fix a Muffler Instead Of Buying New?

It is possible to have the lousy muffler fixed, but this could cost a lot more because whatever part has been damaged needs to be fabricated by a professional to replace it. 

Doing something like this isn’t easy and can not be done by you. In some cases having this done does not guarantee the complete fix of the muffler, as they may continue to experience leaks and restrictions; this is why mechanics advise that you get a new muffler. 

The best way to eliminate a muffler problem is to replace the muffler or have a muffler deleted utterly. Completely replacing the muffler will eliminate any chances of a problem arising again. A problem may arise if the issue is from other parts of the exhaust system. 

Another way to solve the muffler problem is to have a muffler delete. A muffler delete is a process of completely removing the muffler. Before doing this, you must consider the advantages and disadvantages. 

You can achieve a louder sound when you remove the muffler from your vehicle. The problem with muffler delete is that it is illegal in all states in the US. One reason the muffler deletion is illegal is because of the level of sound emission that comes from it.

You can also achieve better gas flow with a muffler delete, and the restriction caused by the muffle is no longer there. Here’s an article I wrote about muffler delete in more detail: Muffler Delete Ultimate Guide: Cost, Sound, Mileage & Power


The muffler is an essential part of the exhaust system that helps dampen sound. When it becomes faulty, it cannot reduce the sound created by the exhaust gases. A faulty muffler also comes with other signs, like exhaust gas smell in the vehicle, check engine light, and poor fuel economy. 

An engine failure is one of the most disturbing signs of a failing muffler. The muffler or any other significant part of the exhaust system will affect the engine’s performance. To solve a damaged muffler, you can either replace the muffler or have the muffler removed utterly. 

Ifandi L.

Ifandi L.

Passionate about everything mechanical. Ifandi has been involved with motorcycles and cars since the old days - in his family's auto parts shop. Want to keep in touch? Scream "STRAIGHT PIPEEEEE" at the top of your lungs and Ifandi will show up.

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