What's THAT Smell?!? Important Reasons Why Your Car Smells Bad

The smell of a freshly-bought vehicle is intoxicating, but when your car starts to smell bad, then you need to pay attention. There are actually two basic kinds of odors that you normally experience: smells due to a mechanical problem, or smells from an outside cause.

Those caused by mechanical issues can indicate many things, such as a malfunctioning heater, leaking oil, damaged catalytic converter, and many others. The second one can come from the outside factors, such as cigarette smoke or a half-eaten hamburger you forgot to take out seven months ago. This type of odor may be easier to fix, and in this case, just needs a thorough vacuuming of the interiors and maintaining a clean car.

Diagnosing whether a bad odor is due to mechanical or environmental issues, however, takes some practice. Just as some experienced mechanics have an "ear" for knowing where a car squeak is coming from, there are also those who have a "nose" for diagnosing what problem it is. We can't promise you'll become an overnight expert here, but we've taken a page from the experts' guidebook by spilling out some of their secrets.

What it smells like Sweet

Before you assume it's a mechanical problem, make sure that it's not the maple syrup you drizzled on your pancake early this morning. If you're positive it's not, then chances are you're dealing with a coolant problem.

As the name suggests, a coolant is necessary to raise the boiling temperature of your car's engine. This prevents it from overheating.

A car that smells eeringly sweet might mean that your coolant is leaking somewhere. Coolants are made from toxic ethylene glycol, and they smell really sweet like maple syrup. When you vaguely smell it somewhere, then chances are your coolant is leaking from a radiator cap, a heater hose, a malfunctioning cylinder head or an intake manifold gasket.

What it smells like Pungent, Sharp, Acidic

Do you have a habit of riding your brakes raw or leaving your parking brake on? If you do, and you smell something like burnt paper, then you've probably burned your brake or clutch in the process. Or another reason might be that your clutch is slipping or in need of adjustment. The simple solution is to stop riding the clutch pedal too hard, or have your clutch replaced.

What it smells like Burnt Oil

This indicates that oil is leaking on your car's exhaust system. When oil drips on any of its parts, it burns. You'll easily know it because the smell is really bad. Another indicator: you'll notice a lot of thick blue smoke. The solution here is simple: plug that leak.

What it smells like Sulfur Smells

Smells like rotten eggs? Then it's probably bad catalytic converters. Catalytic converters modify exhaust gases to lessen the harmful emissions. When they're not working properly, they give off that sulfuric smell that's similar to rotting eggs. The best way to solve this is to replace the catalytic converters and fix what's causing it to malfunction in the first place. The bad news? Catalytic converters are expensive, so prepare to spend a lot if your car is not covered under a warranty any longer.

By the way, there are some lubricants used in manual transmissions that also has a similar smell when they age. You'll easily know this is you find them leaking somewhere. When you encounter this problem replace the lubricant and check the root cause of the leak.

What it smells like Raw Gas

It's the easiest one to recognize, since gasoline has that distinctive, strong smell. Keep in mind that a small amount of gas smell is okay if your have a carbureted vehicle. Or if your car model is old -- before the 80's, or perhaps earlier. However, if yours is fuel-injected, then a strong gas odor indicates that something's really wrong with your car. This is especially true if your car is just parked inside your garage, or the weather is warm.

There are many reasons why this is happening. It can be damaged fuel pressure regulators, stuck injectors, or a leaking fuel-tank vent hose. There are actually a lot more probable reasons, so we'd suggest you seek the help of a good fuel mechanic to pinpoint the true cause of the problem.

What it smells like Musty, Moldy, Smell

If there's a mildewy or moldy smell somewhere, then your water is probably getting inside your car (and have been collecting there for some time). Check for damaged window seals that can encourage water to come in, or look for leaky doors as well. Check out the roof of the car for signs of mildew lines, or look for wet seats and carpeting.

Another cause may moisture that's condensing inside your air con evaporator.  It almost smells like gym socks that haven't been washed for 3 months. One way to lessen the smell is to turn off your air conditioner a mile from home and then run the fan on high to help the system to dry out.

How to Get Rid of Bad Car Odors

1. Vacuum your car

Believe it or not, vacuuming your car can actually take out a lot of those bad smells. Of course, it's not the answer to anything, but it's the best way to start.

2. Use baking soda or charcoal

If, after vacuuming, the odors still seem to linger in the air, then you can use baking soda, charcoal, or other commercial products that are specifically designed to do it.

Leave an opened baking soda box in the corner of the trunk for continuous odor absorption. For carpets and rugs, sprinkle them with baking soda, leave for a couple of minutes, and then vacuum.

Charcoal can also do a fairly good job of absorbing odors, and they're cheap. The downside, however, is that they can be messy, especially if you're using regular charcoal.

3. Use ion generators or air purifiers

When baking soda and charcoal aren't enough, try car air purifiers. However, it's not guaranteed that they always work, so make sure you have a backup plan.

4. Hire a professional to do it

This is your last resort, which is often the most effective in most cases. If your car's odor leans toward mildew and smoke, try ozone. Ozone-generating purifiers, however, work best when done by a professional, since doing it by yourself may be dangerous to your health.

You can actually buy ozone generators in the market, but it would be best to have a professional do it for you, instead. That way you're assured that all the persistent car smells are eliminated once and for all.