Exhaust Smell in Your Car Can Be Due to Different Things

image - dual chrome exhaust tailpipeThe car exhaust system neutralizes the harmful fumes that come out of the engine. It is important to have your car checked out if you start to notice any odd odors or exhaust smell inside the car, as this can mean some major problems in the exhaust system or engine. If you experience any eye irritation, or you notice a smell like rotten eggs, a sweet smell or an odor of gasoline, you should have your car checked as soon as possible. Bring your car to a local AAMCO Minnesota auto shop for a complete inspection and diagnostics.

How a Car’s Exhaust System Works

Exhaust Header or Manifold

The exhaust header, or manifold, makes it easier for the engine to push exhaust gases out of the engine cylinders. In cars with fuel injection, the oxygen sensor is mounted in the exhaust header and is controlled by a computer. If the oxygen sensor is faulty or has failed, the computer can’t calculate the air/fuel ratio, so it “guesses”, which affects the engine’s performance, and this can affect many other systems as a result. If you are experiencing a strong smell of gasoline as you drive, the oxygen sensor is one of the first things to check.


image - exhaust manifold

The exhaust travels through connected pipes until it exits through the last one – the tailpipe. These interconnected pipes throughout the system do more than just help the exhaust move; they cool the pollutant gases and guide them through the catalytic converter.

Catalytic Converter

The catalytic converter changes the harmful carbon monoxide and hydrocarbons to water vapor and carbon dioxide before they exit through the tailpipe. This reduces impact on the environment because the elements being emitted from the car have been broken down into more basic forms. Some converters also reduce harmful nitrogen oxides. If the odor you are smelling is that of rotten eggs, then the catalytic converter is probably failing. The rotten egg smell is because the converter is not breaking down the sulfur pollutants created by the engine. Catalytic converters can’t be repaired – they must be replaced.


The “catback” is a system of pipes between the catalytic converter and the tailpipe. These pipes, running along the bottom of the vehicle, experience a lot of wear and tear, including harsh temperatures, damage from obstacles, rough roads, and exposure to weather which can lead to rust.

Muffler & Tailpipe

An internal combustion engine runs by creating controlled explosions, so it makes a lot of noise. You don’t hear most of this noise because the muffler, if it’s doing its job, reduces (muffles) the noise to a low level as the exhaust leaves through the tailpipe. The muffler also sees a lot of wear and tear, along with the tailpipe, as they constantly go through heating and cooling between extreme temperatures.

Exhaust System Leaksimage - Mechanic and customer looking at exhaust system under car on lift

Exhaust leaks can occur in many places along the line of all the interconnected parts that make up the exhaust system. If you smell the exhaust inside the cabin of the car, the leak is possibly somewhere near the air intake vent, under the hood. The leak might be somewhere in the exhaust pipe system that runs the length of the car, or even in the muffler, but the smell won’t be so powerful. Hydrocarbons are processed in the catalytic converter, which is located behind the engine, near the exhaust manifold. So, if you smell any exhaust, it’s probably escaping, or leaking, before it reaches the converter.

Causes of Exhaust System Leaks

We’ve all seen it – a rusted muffler riddled with holes laying in the middle of the road. It fell off someone’s car, and chances are the entire exhaust system (maybe the whole car) looks like that poor, old muffler. That’s why it is important to have the underside of your car visually inspected from time to time.

Internal Corrosion

Internal corrosion is a major cause of exhaust system leaks, and is the main cause of system failure. When moisture condenses in the system, it reacts with the iron in the steel, causing acidic buildup and rust. This can eat right through the metal of the pipes, muffler, and other vital components of the exhaust system, causing leaks, structural weakness, and operational failure.

External Corrosion

External corrosion is caused by weather related road conditions. Depending on where you live, during the winter the roads might be treated with chemical deicers, salt, and sand. All of this, combined with the snow, ice, and harsh temperatures, really beats on the underside of your car – and that’s where the exhaust system is. The constant barrage of different compounds, including plain old water in the form of rain, snow, and ice, gradually eats away at the various parts of the exhaust system.

Driving Conditions and Habits

Where you live and the road conditions around you dictate much of the wear and tear on your car, particularly the exhaust system. Rough, dirt roads obviously will have a higher degree of impact on your car overall than smooth highways and city streets. Additionally, how you drive those roads is a factor. Short trips versus long hauls have different effects on your car’s systems. Whether you speed along those bumpy, dirt roads or are constantly stuck in stop-and-go traffic in the city – it all adds up to things like extreme heating and cooling, debris causing damage, and stress to systems that are not the exhaust system, but that can affect it. As mentioned earlier, if the oxygen sensor goes out, the engine will burn too much fuel, too hot, which can affect the exhaust system and cause undue heat to pass through.

Come to AAMCO Minnesota for All Your Car Repairs & Maintenance

You need an experienced automotive technician who can diagnose the problem and honestly tell you what needs to be done when something is wrong with your car.

If you have questions about your car’s exhaust, engine, transmission, repair or maintenance needs, AAMCO Minnesota can help. Stop by or call a local AAMCO Minnesota repair shop for a Multi Point Vehicle Inspection of your transmission and related systems. We can handle all your scheduled car maintenance and repairs, from brakes and oil changes to factory recommended maintenance and full transmission replacements.

Other Articles About Car Maintenance & Repair

Take the Fear Out of Transmission Repair

What is a Torque Converter?

Signs Your Alternator is Going Bad


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AAMCO Minnesota Transmission shops are locally owned and operated.

AAMCO Hopkins

10921 Excelsior Blvd #117 | 10921 Excelsior Blvd #117, MN, 55343

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At AAMCO Hopkins, MN we believe in the value of good, honest work and giving you and your family the peace of mind a safe, reliable car provides on a daily basis. From transmission repair and rebuild to brake service, air conditioning repair, auto tune ups, check engine light and car maintenance, AAMCO of Hopkins is your one-stop shop for car repairs and maintenance. Trust the transmission experts at AAMCO of Hopkins transmission repair to diagnose and repair your vehicle right the first time and back it with the best nationwide warranty. At AAMCO Hopkins transmission and car repair we know all vehicle makes and models and have the latest in diagnostic tools and technology. We are your total car care and repair specialists.

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AAMCO Minneapolis

5231 West Broadway | Minneapolis, MN, 55429

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Transmission repair and rebuilds are our specialty. From transmissions to brakes, radiators, air conditioning repair, tune ups, check engine light diagnosis and car maintenance, people who know call AAMCO Minneapolis Transmission Repair and Auto Services. Our expert technicians use the latest tools and technology to diagnose and repair your vehicle. From automatic and manual transmission repairs, clutch service and replacement, and more, we know all vehicle makes and models. We back our work with the best nationwide warranty. AAMCO of Minneapolis, MN is your one-stop transmission rebuild and total car care center.

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AAMCO West St. Paul

1571 S Robert St | St Paul, MN, 55118

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AAMCO Transmissions West St. Paul is your Twin Cities one-stop shop for transmission repairs, rebuilds, and car maintenance. Our certified technicians can handle any transmission repair or rebuild, as well as auto repair and maintenance service for your vehicle. You can rely on our mechanics for automatic and manual transmission problems and rebuilds, clutch service and replacement, and more. We use modern computer diagnostics to identify transmission and engine issues so we can repair your car quickly and get you back on the road. We work on all makes and models, including 4x4s.

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AAMCO Fridley

940 Osborne Rd NE | Minneapolis, MN, 55432

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At AAMCO Fridley we believe in performing honest and affordable transmission and auto repair services. We do the job right and get you back on the road safely and reliably. From transmission repair and rebuild to brake service, air conditioning repair, tune ups, check engine light and car maintenance, AAMCO Fridley, MN is your one-stop auto mechanic. Trust AAMCO’s expert auto technicians to use the latest tools and technology to diagnose and repair your vehicle, and back it with the best nationwide warranty. At AAMCO of Fridley, Minnesota we know all vehicle makes and models and have the latest in diagnostic tools and technology. We are your total car care specialists.

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AAMCO Maplewood

1905 County Rd D E | Maplewood, MN, 55109

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People come to AAMCO of Maplewood, MN because we care about making sure you car is running safely and reliably. You can count on us for all your automotive repairs and maintenance. From transmission repairs and rebuilds to brakes, radiators, air conditioning, check engine light and tune ups. AAMCO Maplewood transmission and auto repair technicians use the latest technology to diagnose and repair your vehicle right the first time - and we back it with the best nationwide warranty. At your local Minnesota AAMCO of Maplewood we know all vehicle makes and models - we're your one-stop total car care specialists.

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Our mission is to provide the best auto repair and maintenance in Minnesota. With 6 convenient locations and nearly 50 years in business, you can count on your locally-owned Minnesota AAMCO Center to provide expert transmission repair, brake service, tune-ups, oil and filter changes, electrical system repair, fluid service, and much more for your car, truck, or SUV.

Our comprehensive 36-step ProtectCheck® Inspection, expert technicians, and no-nonsense pay-only-for-what-you-need approach makes us the most trusted name in car care. Come see why people who know go to AAMCO.

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