So, you’re noticing a rotten egg smell while your vehicle is running…
It could be several things but the most common cause is a broken or clogged catalytic converter. This part of your car’s emissions system works by converting harmful gases like hydrogen sulfide into harmless gases. However, if it’s broken or working incorrectly, you’ll smell the hydrogen sulfide instead of the odorless sulfur dioxide, that’s your rotten egg smell. Unfortunately, you probably need a new catalytic converter. Driving with it broken is dangerous and can lead to a car fire.
A failing fuel pressure sensor is another issue that can cause the smell. 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. If you drive a manual car, another source of the rotten egg smell could be old transmission fluid. It’s recommended that you change your transmission fluid regularly. If you haven’t, 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.