Symptoms of an Exhaust Leak

Unless you’re a gearhead or an enthusiast, there’s a great chance that you don’t think about your car’s exhaust very...

Unless you’re a gearhead or an enthusiast, there’s a great chance that you don’t think about your car’s exhaust very often. It’s just one of those things that does its job, silently, out of the way. It’s not until something goes wrong that many people start developing feelings toward their car’s exhaust, usually negative.

Leaks are one of the most common issues that can happen to your car’s exhaust system, but the signs of a problem aren’t always obvious. You may hear a noise or smell something funky, or you may not. Diagnosing and fixing an exhaust leak isn’t hard, but you’ll need to know how and where to get started. Car Bibles’ editors have been on the wrong side of more than one exhaust system throughout the years, and are here to help you figure it out.

Let’s get started.

What Is an Exhaust Leak?

“How can my exhaust be leaking?” That’s a legitimate question, especially because your exhaust system doesn’t hold any liquid. Exhaust leaks happen when some of the gas that is produced inside the engine leaks out before it exits the tailpipe. This may not sound like a huge deal, but it can have consequences beyond killing baby penguins in the arctic.

When exhaust leaks happen, they can cause issues with sensors that are placed along the exhaust system, which are in place to help the engine determine how much or little fuel and air it needs to consume to keep running properly. Beyond that, the exhaust fumes, if plentiful enough, can become harmful to you or your passengers.

Exhaust Leak Symptoms, Causes, Issues

You may notice a few main symptoms if your car is experiencing an exhaust leak. Strange noises coming from the engine bay or from around the catalytic converter (under the middle part of your car) may indicate an exhaust leak. You may also notice a drop in fuel economy or a check engine light as one or more sensors report failure or incorrect operation.

How To Identify An Exhaust Leak

If you suspect there’s a leak in your exhaust system, there are a few steps you can take to identify the problem. First, make sure that your car hasn’t been driven for any period of time before you start handling the exhaust components. Like everything else, they get hot while the vehicle is running. Put the car up on jack stands and take a look at the underside. Are there any immediately apparent points of damage to the various heat shields, piping, mufflers, or connection points? If so, you’ve got a pretty good idea of the culprit.

Next, you can take a listen while the vehicle is running for any wheezing, whistling, or whining sounds. As air escapes, it tends to make funky sounds that you’re not used to hearing. It’s a good idea to have a friend rev the engine while you’re investigating so that you can hear the air as it rushes by.

How To Resolve an Exhaust Leak

The answer here is to repair any components that you observe to be part of a noticeable leak, but it’s not always that straightforward. If you’re able to do the work yourself, that’s great, but you may also need to chase down any damaged or malfunctioning sensors. Even if you fix the leak, leaving a sensor out of whack will still get you a check engine light and may still interfere with proper fuel economy and other operations as the engine thinks it needs to compensate for a leak.

Car Bible’s Glossary for Exhaust Leak

Welcome to Bible School!

OBD

OBD, or onboard diagnostics, is your vehicle’s way of observing its own performance and health. When there’s an issue, the car’s computer generates codes that correspond with specific problems, which can be scanned using an OBD-II tool.

Exhaust

Your car’s exhaust system is way more involved than just the muffler or tailpipe that you can see. It includes everything from the engine to the back, and includes sensors, resonators, and other components meant to remove as much harmful material from the exhaust gases as possible. It’s also designed to reduce noise.

Catalytic Converter

Catalytic converters use metals such as palladium, rhodium, or platinum to help convert nasty exhaust gases into less-nasty exhaust gases.

The Exhaust Leak Questionnaire

Car Bibles answers all your burning questions.

Q. How Much Does It Cost To Fix An Exhaust Leak?

A. Depending on your car, how bad the problem is, and where you live, fixing an exhaust leak can be quite cheap. Count on spending somewhere between $100 and $500, with most of that cost coming from labor.

Q. How Hard Is It To Fix An Exhaust Leak?

A. Replacing exhaust components isn’t the hardest thing to do, but you’ll need to be able to identify the problem. That can take experience and a scanning tool, but most home mechanics should be able to complete the job.

Q. Can I Ignore An Exhaust Leak?

A. Do you like killing the environment? An exhaust leak may not be the most dramatic problem with your car. In fact, it may seem like there’s nothing wrong at all, but ignoring an exhaust leak can allow more harmful stuff out into the atmosphere than you think. In a worst-case scenario, exhaust fumes could trail into your car’s cabin.

The Exhaust Leak Video Tutorial

Car Bible’s Favorite Exhaust Leak-Related Products

It can be hard to find products to help you diagnose and fix exhaust leaks. That’s why Car Bibles’ editors have chosen a handful of our favorites to get you started. They include Mechanix Work Gloves, the Innova CarScan OBDII Scanner, and Pro-Lift Jack Stands.

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Chris Teague

Chris TeagueChris used a passion for all things automotive into a good excuse to leave the corporate world and pursue a career as a writer and podcaster. Originally from Tennessee, he now lives in Maine, where he’s become an expert on how “you can’t get there from here.” Contact the author here.