It serves a vital function for the health of your vehicle and the environment, but how do you know when it fails?

A vehicle exhaust system works to collect and expel the gases produced in every internal combustion engine. Not only is it essential to get rid of harmful products, but it's also in line with global regulations to minimize harmful emissions. The entire exhaust system consists of the exhaust manifold, catalytic converter, muffler, sensors, and exhaust pipes. Vehicle mufflers also reduce noise from the whole setup. Maintenance is essential to prevent exhaust problems and a costly repair. This guide will help you understand the basics of your exhaust system and how to spot and fix exhaust issues when they arise.

As an internal combustion engine (ICE) uses the ignition of fuel to drive pistons that produce energy, the byproducts formed in the process need to be expelled safely. This system takes care of that. Numerous components make up an exhaust system, including:

This is the part closest to the engine block and is the first step in the emissions process. It attaches to the cylinder head, collects the fumes released from the cylinders, and will burn up any unburnt gases. The exhaust manifold will then direct these gaseous outputs either to the catalytic converter or turbocharger (if the engine is turbocharged). How the exhaust manifold is designed is quite important to performance, and some larger engines may have two exhaust manifolds. Manifolds are mostly made of stainless steel, aluminum, and cast iron to allow them to withstand high temperatures.

These are an essential part of any modern combustion engine, and there are generally at least two of these in the system, although V6 or V8 engines with two manifolds will obviously have more. The first oxygen sensors are found in the exhaust manifolds. By measuring how much oxygen is present in the exhaust fumes, the onboard computer can determine if more or less fuel is necessary to achieve maximum efficiency and performance. The other sensors are found after the catalytic converter.

Gases from the engine can be reused in turbocharged cars, but we deal with turbocharging in our in-depth post here. In non-turbo cars, exhaust gases are directed to the catalytic converter from the manifold, where a combination of catalysts is used to reduce the harmful emissions. At this stage, hydrocarbons and carbon monoxide are transformed into water and carbon dioxide, while nitrogen oxides are reduced in the process. Emissions regulations mean catalytic converters are a requirement on all cars.

Cars that run on diesel, such as the Jeep Gladiator EcoDiesel or Ford F-250 Super Duty, have a diesel particulate filter additionally, which serves to capture the heavier elements found in diesel such as soot and ash. You can read more about diesel particulate filters here.

There are numerous pieces of pipe that connect all the components in the system. These are commonly referred to as exhaust pipes and run along the length of the underbody of your car.

Mufflers are added to reflect and absorb the majority of the sound traveling through the system. Oftentimes, this is not sufficient and a resonator needs to be added, too. The latter focuses specifically on eliminating high-pitch frequencies, humming, and buzzing. These work together to dampen some of the harsher engine sounds.

The final pipe tip is where the product of the entire system is finally expelled. This is usually at the rear of the vehicle, and sometimes dual outlets are installed as often seen on sportier models. On trucks, these may even be positioned on the sides instead. Naturally, electric vehicles don't have these (or have faux-exhaust tips for looks), as there are no emissions to expel in EVs.

This diagram of a typical exhaust system.

As with any complex mechanical system, problems are bound to crop up from time to time. They could be as simple as a build-up of rust or as severe as a complete exhaust system failure. Knowing how to spot them and what steps to take to remedy them is essential. Here are some of the most common problems:

A vehicle's exhaust system isn't there just to make it sound quieter; it serves an essential role in operations as well as ensuring the car meets roadworthiness and emissions regulations. Specialized systems can even improve the overall specs of a vehicle by increasing engine outputs or fuel efficiency. If you want your car to run at its best, it is important to maintain and regularly check before a repair to an exhaust system is needed, or the system has already failed.

As with all automotive work, the exact price will vary from model to model and mechanic to mechanic. However, there are some average figures to help you estimate the total cost. The exhaust manifold itself will set you back around $500, while the mufflers usually cost approximately $150 each and the downpipes $50. Beyond the exhaust system parts, there are labor and time costs, too. Overall, the final price of a full exhaust system installation or replacement should be somewhere in the range of $450 and $1,200, but as much as $1,500 is possible. These are not taking performance parts into account. You can save a little by doing the work yourself, and some dealerships may offer a discount or free service if you buy the parts from them.

The resonator does exactly as the name suggests. As the sound from the engine travels through the chamber, it creates a resonance effect that helps to cancel out some of the higher frequencies and other annoying noise, like buzzing. Most of the annoying sounds are thereby removed from the final engine note. However, it doesn't affect the volume; that is the job of the muffler.

This refers to a modification in the system that's designed to improve airflow. It's installed after the catalytic converter (hence the name) and comprises all the piping and the muffler after the cat. A larger diameter of pipe can be used, and the benefits of having a cat-back exhaust system installed include performance gains, a louder sound from the exhaust pipes, and even improved fuel economy.

Back pressure is a natural part of how an exhaust system works, and occurs when there are impediments to the airflow through the exhaust system. Restrictions occur inevitably as gases are funneled through the system to the catalytic converter, the resonator, and the muffler, however. The idea that backpressure is needed for an engine to run well is misguided, however, as it's naturally part of the process, whether desired or not.

There are many organically loud cars out there, from the Mercedes-AMG E63 to the Lamborghini Huracan Performante, which rank among the loudest. However, any vehicle can increase the sound output of its engine with a complete exhaust system replacement. The muffler is the noise-reducing culprit, but a full overhaul is usually necessary if you want to really make an entrance. Some of the best types of exhaust systems for a sonorous soundtrack come from Flowmaster and include the Outlaw and American Thunder kits. The latter is often used on pickups in the USA, like Chevy trucks. Magnaflow also offers a capable and pleasurable setup.

Morgan has always had a love for the written word, which is why he obtained an Honours Degree in English Language Studies. Having spent several years as an editor for a variety of trade magazines, he decided he wanted to try something a bit more exciting and hands-on. This led him to CarBuzz, where he has been writing and editing reviews and blog posts since 2018. A level-headed academic, Morgan enjoys reading about the latest tech in the automotive industry, even though he drives an economical hatchback.