Your parents probably taught you to have common sense. When it comes to your vehicle, common scents can also come in handy. Different smells may tell you about some conditions in your vehicle that need attention.
For example, you know what rotten eggs smell like. If you smell them around your vehicle, it means sulfur can't be far away. Here's a surprising fact: Gasoline has a little sulfur in it. There's a device in your exhaust system that's supposed to convert it to something that doesn't pollute the atmosphere. That device is a catalytic converter. If you are smelling rotten eggs, maybe your catalytic converter is wearing out. But it could also be a problem with your fuel injectors. Either way, something's rotten that should be repaired.
Ever smell something sweet around your vehicle, maybe a little like pancake syrup? If you sniff out a little sweetness just when your engine is warming up or after you shut off your engine, you might be smelling some coolant (anti-freeze). If it's leaking, then you may be getting a whiff of ethylene glycol, one of the coolant's components. If the odor is strong inside the car, it could be a leaky heater core. This is important to get checked out because a leak in your vehicle's cooling system can eventually cause expensive damage.
How about that distinctive smell of gasoline? You could have a leak in your gas tank, a hose that vents your gas tank or a leak in a fuel injector line. A gasoline leak needs to be tracked down since it could catch fire. It can also be bad for your health if you breathe it in all the time.
When you step hard on the brakes, ever smell something like a rug's in fire? That could mean you've just overheated your brake pads. If you detect that smell just driving around town, one of the brake calipers could be stuck. To figure out which wheel has the problem, get out of your vehicle and smell each wheel. It will likely be obvious where the problem is.
Here's one last smell. Ever had your oil changed and right after you picked up your vehicle it smells like something's burning around the engine? That's because sometimes a little oil leaks onto the metal when the filter is changed or the oil is poured in. It's a useful smell to know. Because of you smell burning oil and you haven't had your oil changed recently, that could mean you have a leak in your engine. It could be a gasket or a seal, but it also could mean the start of more serious issues.
All of these things are signals that you should discuss with your service advisor to get them checked out.