Cars

My Car Smells Like Rotten Eggs: Why It Smells and What to Do

Few things are more aggravating than suspecting something is wrong with your car. There are obvious signs like loud noises or weird movements, but there are also more subtle things like an unusual smell in or around your vehicle. Smells are something you never want to overlook. They could signal that something is seriously wrong with your car.

What are some smelly red flags?

There are a few common smells that occur in vehicles. If you smell something musty, like old gym socks, while your air conditioner is running, it’s usually a sign of mold or mildew growing inside your AC. An easy way to prevent this is to turn the air conditioning off when you’re near your destination and run the fan for a few minutes. This helps the water on the coils dry out and discourages the growth of bacteria.

If you get a strong smell of rubber, something may be overheating. It could be an accessory drive belt that slipped and is now rubbing against another moving part, which means the belt needs replacing. It could also indicate an overheated clutch plate, which is caused by riding the clutch too often. Electrical issues can also cause things to overheat and wreak havoc on your internal systems.

It’s clear we need to pay attention to the smells in our car, but what’s one of the most common smells to watch out for?

My car smells like rotten eggs

If you notice a rotten egg smell while your vehicle is running, it could mean a few things. The most common cause is a broken catalytic converter. This part of your car’s emissions system works by converting harmful gases like hydrogen sulfide into harmless gases like sulfur dioxide.

When it’s broken or working incorrectly, however, you’ll smell hydrogen sulfide instead of the odorless sulfur dioxide — there’s your rotten egg smell. Unfortunately, you probably need a new catalytic converter. Driving with a broken one can lead to higher temperatures in your exhaust system, which can ultimately lead to a car fire.

Another issue with catalytic converters comes from a failing fuel pressure sensor. This sensor controls where the fuel in your car goes. If it fails to regulate, your catalytic converter can become clogged with too much oil and overwhelm the emissions system. This leads to the same problem: Those harmful gases are not being converted the way they should be, leading to an odor.

Another source of the rotten egg smell could be old transmission fluid. If you drive a manual car, it’s recommended that you change your transmission fluid regularly. If you haven’t in a while, it can leak into other areas of your car and can cause a smell once it stagnates.

The good news is that once you figure out where the rotten egg smell is coming from, you shouldn’t need to do any deep cleaning to get the smell out. Fix the problem and the smell will disappear.

Of course, not all smells are a guaranteed trip to the mechanic. If you smell something like, for example, rotting fruit, it’s a good idea to look under your seats for something you or your kids may have left. Although it would give your mechanic a chuckle, nobody wants to pay for diagnostics on a forgotten apple!