Top 8 Reasons Your Car Stinks

Figure out why you're suffering from bad car smells

When your car smells a little off, it’s trying to tell you something. Like the distinctive sound of a rattling timing chain, or clicking of a bad CV joint, bad car smells often indicate that there's something wrong somewhere in your car. And like those other little hints, paying close attention to the specific way your car smells can help you track down the culprit and even fix it.

Here are seven of the top reasons your car stinks, and what you need to do about it.

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Your brakes or clutch need attention

Smoke coming from a car tire.
Joseph O. Holmes / Moment / Getty

Associated smell: Acrid

When does it smell: Usually when the vehicle is moving, and sometimes specifically when the brakes or clutch are applied.

Why it Smells

Harsh, acrid smells typically mean that either brake or clutch material has been burnt. Riding your brakes or leaving the parking brake on are both great ways to make your car smell like this. Of course, a stuck caliper or frozen parking brake cable can also do the job for you.

A burnt clutch smells very similar to brake pads that got too hot, and it can be caused by riding the clutch. It can also mean that your clutch is slipping, either because it’s worn or because it needs to be adjusted. In systems with hydraulic clutches, a slipping clutch can also indicate a problem with the hydraulic system.

If it's more of a burning rubber smell, then you might want to do less peel outs.

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Your heater core is leaking

Antifreeze being poured into an overflow bottle in a car.
Jane Norton / E+ / Getty

Associated smell: Sweet, candy, maple syrup

When does it smell: The heater is is turned on, the engine has warmed up, or sometimes after you shut the engine off.

Why it Smells

Antifreeze smells sweet. It smells so sweet, in fact, that it has to include a bittering agent by law. This is to help prevent animals and children from drinking what smells like a delicious treat.

If you smell something cloyingly sweet in your car, and you’re pretty sure that you didn’t accidentally dump maple syrup down your heating vents, then you’re probably smelling antifreeze. It’s probably the heater core if you smell it strongly inside the car, and if you notice a filmy fog form on the windshield when the heater is on, that’s another hint.

Also, if there is antifreeze on the floor inside your car, that is another good clue. If you can't afford to fix it, bypass the leaky core and check out some car heater alternatives.

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Water is getting where it doesn’t belong

A foggy windshield in a car.
Rob D. Casey / Photographer's Choice / Getty

Associated smell: Musty

When does it smell: All the time, or after a rain.

Why it Smells

A moldy or mildewy smell indicates that water is getting in your car and then pooling there. Leaky door or window seals can allow water in, so if you find wet seats or carpeting, then that’s probably the issue.

However, the A/C evaporator is a very common cause of this particular odor.

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You have an oil leak

Oil being poured into a funnel.
Vstock / Getty

Associated smell: Burning oil

When does it smell: The engine is hot, whether or not you're driving.

Why it Smells

When oil drips on any part of the exhaust system, it burns. This smells really bad, and it can also create copious amounts of thick, blue smoke if the leak is bad enough. The fix is simple enough: get rid of the leak. Your driveway will also thank you.

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Your catalytic converter is busted

A mechanic removes a plugged catalytic converter.
Joe Raedle / Getty Images News

Associated smell: Sulfur

When does it smell: The engine is running.

Why it Smells

Catalytic converters are emissions control components that alter exhaust gasses to reduce harmful emissions. When they don’t work right, you sometimes end up altering exhaust gasses to smell like someone spent most of last week throwing rotten eggs at your car. The fix is to replace the catalytic converter and also repair whatever caused it to fail, assuming it didn’t just wear out.

Some lubricants that are used in manual transmissions and transfer cases can also smell like sulfur as they age, which you may notice if they start leaking all over the place. If that’s the problem you’re dealing with, you’ll want to change the lubricant out and figure out where the leak is coming from.

of 08

Gas is getting where it doesn’t belong

Gas leaking from a car.
Joanne Dugan / The Image Bank / Getty

Associated smell: Aromatic hydrocarbons (raw gas)

When does it smell: All the time, when the engine is running, or on especially hot days.

Why it Smells

If you smell a strong gas odor coming from your car, chances are pretty good that something has gone very, very wrong. Some amount of gas smell is okay, especially if your car is carbureted, but fuel injected vehicles typically shouldn’t smell strongly of gas.

Leaky fuel lines, stuck injectors, bad fuel pressure regulators, and a host of other issues can all lead to fuel leaks or dump enough gas into the engine to cause a smell. In any case, it’s usually a good idea to track down the source of the leak sooner rather than later.

of 08

Your groceries rolled under the seat last week

Groceries in a car.
Westend61 / Getty

Associated smell: Death

When does it smell: After you get home from the grocery store and notice they shorted you a couple bananas.

Why it Smells

Most of the reasons a car can smell have to do with some kind of mechanical breakdown or failure, but there are a lot of outside sources as well.

So before you take your car into your favorite mechanic to ask why it smells like death in there, make sure to check under the seats. There's always a chance that some produce, a dirty diaper, or some other malodorous item rolled under there.

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Someone has been lighting up in your car

A man lights up a cigarette in his car.

KatarzynaBialasiewicz / iStock / Getty

Associated smell: Smoke

When does it smell: All the time

Why it Smells

This one is a little more obvious than the others, and you probably already know why it smells. Smoke from cigars and cigarettes represents one of the most persistent bad car smells. Even special measures, like smoking with the windows rolled down, doesn't really help that much.

Once your car has been affected by this source of bad smells, fixing it is a monumental task. Smelly remnants settle into the carpet an upholstery, coat the windows and dashboard, and no amount of air fresheners will help.

For help, check out our full guide to removing cigarette and smoke smells from cars.

Once you've identified the source of your bad car smells, it's time to fix the problem. Check our our full guide to cleaning and removing bad car smells, and you'll be one step closer to recapturing that long-lost new car smell.

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