Car Smells Like Rotten Eggs
That sulfur smell is hydrogen sulfide from the catalytic converter. A little is normal; a strong smell that keeps up usually means the converter is working overtime.
What it feels like
- A sulfur smell at the tailpipe, strongest right after you shut the engine off
- It gets worse under hard acceleration
- The smell comes into the cabin through the vents
- Sometimes paired with a check engine light
Codes that usually produce this
Check these first, in this order
Free checks first. Nothing here costs money except the fuel you burn.
- 1
Note when the smell appears. Right after a fill-up points at fuel quality rather than a part.
What you'll seeA smell tied to one tank of fuel usually clears on the next fill.
- 2
Read the codes and check for a rich-running condition on the scanner fuel trims.
What you'll seeLong-term trim inside plus or minus 10 percent. A negative number means the engine is running rich.
- 3
Check the engine coolant temperature on the scanner once warm.
What you'll seeAround 195F to 220F. An engine stuck cold runs rich and overloads the converter.
Stop and get it looked at if
- The check engine light flashes.
- The converter shell glows red after a short drive.
- The smell appears along with a sharp loss of power.