Signs You Have Exhaust System Trouble In Your Car

When To Replace Exhaust System Components

The exhaust system not only helps remove the spent gasses from the combustion chamber but also helps treat the harmful gasses to create non-hazardous counterparts, increases engine performance and efficiency, and minimizes engine noise. All these functions are enabled by a set of components within the exhaust system. The heat from the combustion coupled with environmental factors like moisture, dirt, dust, and other hazards, tend to deteriorate exhaust system components just like any other vehicle part. Failure in the system can be caused due to many reasons but the results are ultimately going to affect overall engine and vehicle performance along with serious safety issues. Therefore, the exhaust system needs to be analyzed regularly and any components that are faulty need to be replaced. 

In this article:

Components Of The Exhaust System

To understand the exhaust system you need to be aware of the various components it holds. The exhaust manifold lets out the gasses from the cylinders into the catalytic converter that does the job of cleaning up the harmful gasses with chemical processes. The gasses then follow the exhaust pipes into mufflers and resonators that dampen the engine noise to a bearable level and tone. The exhaust gasses finally exit through the tailpipe or pipes depending on your exhaust configuration.

An exhaust system failure is not easily detected since it requires you to lift up the car enough to be able to properly assess the condition of various parts. The manifold and cat converter can be even trickier to access depending on the vehicle and engine bay layout. This is why detection of a problem can be missed on routine checkups unless you look for the problem. You will however see signs like clunking noises or the excessively loud engine or other problems that can indicate an issue with the system. The following sections showcase the most vulnerable parts of the exhaust system and the symptoms you will notice as the component fails. 

Exhaust Parts That Commonly Fail


The muffler can last for a long time but exposure to salt from snow and icy roads can cause premature failure or reduce the lifespan. Another cause for muffler failure is damage from rocks and other road debris or from frequent hits from potholes, speed bumps, or any road disturbances. A lousy repair or replacement can also cause muffler failure. 

Mounting Hardware, Hangers, And Gaskets 

The hardware that suspends the exhaust system components away from the vehicle body is constantly under abuse. These are the most susceptible components of the system. Wear and tear over time can lead to broken clamps, brackets, torn hangers, and deteriorated gaskets. Luckily these components are not only easy but also cheap to repair. 

Exhaust Pipes 

Much like the muffler, the exhaust pipe faces similar hazards from road salts and moisture that can stem rust which ultimately leads to rust holes or complete corrosion of the pipes. Physical damage can also be a factor that can reduce the service life of exhaust pipes. Read one to learn more about exhaust pipe failure and how you can fix it

Cat Converter 

Generally, catalytic converters have a long service life, but external factors can cause their failure. Cat converter failure usually points to an issue that lies somewhere else in the engine. For example, bad spark plugs or spark plugs wires can prevent complete combustion causing unburnt fuel to enter the cat converter resulting in a partial or complete meltdown. Similarly, a faulty oxygen sensor can produce wrong readings which can cause a change in the fuel mixture ratio and disrupt proper engine functioning, and damage the cat converter in the process. Structural damage can also be a possible cause. The internal structure of the converter is delicate and made of lightweight porous materials. Broken mounting brackets, hangers, off-roading, going over potholes and speed bumps, or any impacts underneath your car can strike the cat converter causing a catalyst fracture.

Signs Of Exhaust System Failure

Here we discuss the common symptoms that various exhaust system components exhibit to help you take quick action and fix the issues before the repair bill becomes larger. 

Reduced Fuel Economy

Starting with the most adverse effect that exhaust system failure brings in - increased fuel consumption. The amount of fuel supplied is actually controlled based on the amount of oxygen present after the combustion process. An oxygen sensor (O2/lambda sensor) present after the exhaust manifold senses the oxygen level in the gasses and the ECU accordingly supplies a rich or lean fuel mix. If the O2 sensor is bad, clogged, or contaminated, the reading is faltered causing the ECU to supply a rich fuel mix to compensate. This eventually increases fuel consumption and drastically impacts the fuel economy of the engine along with the emissions. 

Subsequently, if there is a leak through which the exhaust gasses escape, the O2 sensor will not be able to read the oxygen levels and causes it to direct false readings to the ECU which again will hinder precise fuel delivery and reduce fuel economy. 

Essentially, what this means is that if you start to experience lowered fuel efficiency, then check your exhaust system for leaks and diagnose the oxygen sensor to restore the fuel economy of the vehicle. 

Reduced Power And Acceleration

Similar to how the fuel economy is hit by exhaust leaks and sensor failure, the power produced by the engine is also impacted. You can instantly feel hesitant cold starts along with slower acceleration and pedal response. Overall, the engine does not produce peak power as the fuel supply is not accurate and some of the exhaust gasses are recirculated by the EGR system (which is done not only to reduce emissions but also to increase engine performance) is stopped due to the leak in the system. 

It might surprise you how leaving exhaust gasses can also influence engine performance and power output. In fact, you can even increase engine performance with the right exhaust equipment.

Check Engine Light

Since the ECU closely monitors the exhaust gasses, any disruption in oxygen sensor readings can trigger a check engine light. A different oxygen sensor is used to analyze how well the cat converter is working and so a faulty catalytic converter also causes the ECU to send out warning light. Using a handy code reader can shed some light on the issue. 

Unusual Smells

Using your senses to diagnose and find faults is one of the oldest and most reliable methods of fault detection. So if you start to smell the following odours then checking your exhaust system is a good idea.

Gasoline Smell: Untreated exhaust gasses can smell a lot like gasoline especially if it contains large amounts of unburnt hydrocarbons. If you smell gasoline in the cabin or the engine bay then avoid driving and have the issue addressed first as it can proliferate into bigger problems. 

Rotten Egg Smell: A catalytic converter failure is commonly diagnosed by a rotten egg smell which is a result of hydrogen sulphide. Fuel contains small traces of sulphur which is usually burnt and treated by the cat converter. But if the catalytic converter fails, hydrogen sulphide is released which has a pungent, rotten egg-like smell and is extremely toxic. Have your exhaust system and catalytic converter inspected immediately to minimize any health hazards. 

Burning Smell: Exhaust gasses can reach very high temperatures but the exhaust system cools down the gasses as they reach the tailpipe. If there are a leak at the manifold, gaskets, catalytic converter, etc. hot gasses directly contact the plastic bits and wires found in the engine bay, thus melting them and can even cause smoke and fires along with a burning smell. 

Unusual Noises

One of the major jobs of the exhaust system is to suppress the loud engine noises that result from the continuous combustion process. If you start to notice an increase in the engine noise or hear distinct unusual sounds then there is a likelihood of an exhaust systems component failure.

Hissing Sound: A hissing sound usually emanates from the exhaust manifold and gasket when there are holes that allow gasses to escape through tiny orifices causing a hissing sound. These holes result from worn exhaust gaskets material, rusting, and pitting of metal and can be fixed by either replacing the exhaust manifold, gasket or finding each hole and covering it with heat resistant tape, welding it, or similar solutions. 

Rattling And Dragging Sound: Broken or improperly fitted exhaust pipes, worn mounting brackets, and hangers can cause vibrations along with rattling sounds. Once the pipe is fully broken and is no longer attached it starts to drag along the road as your drive. This is a clear indication of something not being right. Take a look at all exhaust system components immediately. 

Extremely Loud Engine Noise/Roar: The silencer or muffler does the job of suppressing the engine’s loud clatter into a more harmonious and pleasant sound. But with age, the muffler is susceptible to wear and tear and corrosion is one of the factors that lead to its decline. In such cases, it is common to experience the engine noise getting considerably louder as you drive. Inspect your muffler for signs of rust and damage and replace it with new to maintain the factory buzz.

If you observe any of the above symptoms then have your exhaust system checked as failing to do so can not only reduce horsepower and fuel efficiency but also cause serious health and environmental damage as a result of higher emissions.


Q) Can you drive with a broken exhaust manifold or pipe?

Technically you can or may be able to drive with a broken exhaust manifold/pipe, there are many reasons why you should not. It not only causes increased exhaust emissions but can also impact your vehicle’s fuel economy and power, not to mention the safety hazards of inhaling untreated exhaust gasses. You will also be creating a lot of noise as you drive which can attract fines. The heat from the escaped gasses can melt the plastics in the engine bay and even potentially cause fires which is an obvious indication of why you should not drive in such conditions. 

Q) How to fix an exhaust gasket leak?

Usually, the only way to fix the leak is to replace the gasket. But the exhaust manifold gasket replacement can be complicated. You can find detailed steps in this guide to fix the exhaust manifold gasket leak

Q) How to replace exhaust pipes?

The exhaust pipes are one of the most commonly replaced exhaust system components as they are prone to rust, wear and tear and the occasional speed bumper collision. You can refer to our guide on how to identify and fix a broken exhaust pipe


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