What’s That Smell? – Identifying Engine Odors Before They Become Problems

Have you ever gotten in your car and found an unexpected assault on your nose? Most of the time, it’s nothing some fabric deodorizer can’t fix but some smells can indicate underlying problems with your vehicle, and we urge you to investigate. Noticing smells early can help you pinpoint potential troubles with your engine before they become serious issues.


Garber Diagnosing Car Smells


Smells like: Rotten eggs

When: Whenever the engine is on

The Likely Offender: It’s probably excessive hydrogen sulfide in the exhaust. The hydrogen sulfide is supposed to be converted into sulfur dioxide, which is odorless, in your catalytic converter. So if you smell eggs, it’s likely that your catalytic converter is failing or in rare cases, it could be a fuel-injection problem. Either way, it’s best to take your car in and have a professional look at it.


Smells like: Brimstone

When: Anytime, but especially after you finish a long drive

The Likely Offender: While you might think that this smell is much like rotten eggs listed above, this has a more earthy, musky smell while the eggs smell more like old mayonnaise. Luckily (kinda?) this issue also comes with a tell-tale drip under your car that says the high-pressure gear lube needs replacing. You’ll find a thick, oily goo coming from your manual transmission, transfer case, or differential housing units if your car is getting up there in age. If the lube is getting funky, it’s time for a trip to the shop.


Garber Diagnose Car Smellss

Smells like: Maple syrup

When: With a warm engine or just after shutoff

The Likely Offender: You probably smell coolant – it’s made of ethylene glycol which smells syrupy but is actually quite toxic when eaten. Where you smell the sweet waffle topping makes a difference on what the issue is. If you find the odor outside the car means you should check the radiator and radiator cap for leaks. If you smell waffles in the cabin, it’s likely a bad heater core but could also indicate issues with an intake manifold gasket. But in both cases, you should bring your car in to have it looked at.


Smells like: Pure gasoline

When: Parked, usually on a warmer day

The Likely Offender: A gasoline leak from a hose. The vast majority of cars have evaporative-emissions systems that prevent any gas smell from leaking out, so if your car smells like a gas station, then that means raw gasoline is seeping out from someplace it’s not supposed to and you really should get that checked out. Most often the hoses to blame are the fuel-injection line and the fuel tank vent hose.


Garber Diagnose Car Smell

Smells like: Musty old gym socks

When: You crank the AC or heater

The Likely Offender: It’s likely you have some mildew that’s collected in the vehicle’s air-conditioning system. This one isn’t urgent by any means, but it is definitely annoying. When you’ve been running the AC and you have a few miles left on your commute, turn it off and just run the fan until you’re home. That will help evaporate some of the condensation that’s causing the buildup.

Garber Diagnosing Smells

Smells like: Burned paper

When: As you speed up, shifting through gears

The Likely Offender: You probably smell the clutch slipping and burning a little. If you drive an automatic and this is a constant aroma, it could be time to get your clutch disc replaced. However, if you drive a manual and it’s an occasional smell, you could try changing up your driving style to see if that resolves it. Maybe ease off the clutch pedal a little faster? See what works and if the problem persists, bring it in.


Smells like: Burned carpet

When: You’re on the brakes

The Likely Offender: Sounds like the brake pads are overheated. After a hard stop or a long decline, smelly brakes can be pretty normal. But if you get a burnt rubbery smell under normal driving conditions, take your vehicle in for a checkup. Replacing the brake pads or even the rotors to take care of this issue.


Smells like: Hot oil

When: Anytime the engine is hot

The Likely Offender: This one is a no-brainer – engine oil. And it doesn’t smell like the kind of oil you use when you cook; it smells thick, earthy, and acrid. It’s possible that oil is leaking onto the hot exhaust manifold from a leaky crankshaft seal. If this is the case, you’ll find a lot of your oil left on the pavement too – so at least your car is telling you when it’s time to go to the shop? You often find smoke with this smell too, so keep an eye out for that.


No matter what issue you’re facing with your vehicle, our Service Center is ready to help you diagnose and treat your car with the care it needs. Contact a team member today for more information or to set up a time to come in and chat with our certified technicians.

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