If your vehicle is showing rotten egg or sulfur smell coming from the exhaust, here are the most likely causes and the parts you'll need to fix each one.
The catalytic converter is responsible for converting hydrogen sulfide (which smells like rotten eggs) into odorless sulfur dioxide. If it degrades, melts, or becomes clogged, the sulfur smell escapes out the tailpipe.
A failing O2 sensor can incorrectly tell the engine computer that the engine is running lean, causing it to dump excess fuel into the cylinders. This unburned fuel overloads the catalytic converter, producing the sulfur smell.
Worn spark plugs or failing ignition coils cause the engine to misfire, sending raw, unburned fuel directly into the exhaust. This rapidly overheats the catalytic converter and creates a strong rotten egg odor.
A dirty or failing MAF sensor miscalculates the amount of air entering the engine, often resulting in a rich fuel mixture that overwhelms the exhaust system's ability to process emissions.
A mechanical failure in the fuel delivery system can force too much fuel into the engine under high pressure. This extreme rich condition easily overpowers the catalytic converter.