Here are eight of the top reasons your car might stink and what you need to do about it. When does it smell: Usually when the vehicle is moving and sometimes 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 ways to make your car smell like this. A stuck caliper or frozen parking brake cable can also do the job for you. A burnt clutch smells similar to brake pads that get too hot, which can be caused by riding the clutch. It can also mean that the clutch is slipping, either because it’s worn or 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, you might want to do fewer peel outs. When does it smell: The heater is turned on, the engine has warmed up, or sometimes after you shut off the engine. Why it smells: Antifreeze smells sweet. It smells so sweet that it includes a bittering agent by law to prevent animals and children from drinking what smells like a delicious treat. If you smell something cloyingly sweet in your car and you’re sure that you didn’t accidentally dump maple syrup down your heating vents, you’re likely smelling antifreeze. It’s probably the heater core. If you smell it strongly inside the car and notice a filmy fog form on the windshield when the heater is on, that’s another hint. If there is antifreeze on the floor inside your car, that’s another good clue. If you can’t afford to fix it, bypass the leaky core and check out some car heater alternatives. 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, that’s probably the issue. An A/C evaporator is also a common cause of this particular odor. 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 bad and can 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 thank you. When does it smell: When 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, they sometimes alter 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 repair whatever caused it to fail, assuming it didn’t wear out. Some lubricants used in manual transmissions and transfer cases smell like sulfur as they age, which you may notice if they start leaking. If that’s the problem you’re dealing with, change the lubricant and fix the leak. 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, the chances are good that something has gone very wrong. Some gas smell is OK, 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 lead to fuel leaks or dump enough gas into the engine to cause a smell. In any case, it’s a good idea to track down the source of the leak sooner rather than later. When does it smell: After you get home from the grocery store and notice they shorted you a couple of bananas. Why it smells: Most of the reasons a car smells have to do with a mechanical breakdown or failure, but there are also outside sources. Before you take your car to your favorite mechanic to ask why it smells like death, check under the seats. There’s a chance that some produce, a dirty diaper, or some other malodorous item rolled under there. 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, don’t help 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 and 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.
