Mechanics

BAD SMELL COMING FROM SOMEWHERE.

2002 GMC Sierra • 180,000 miles

I have a rotten egg smell coming from the engine compartment. I can smell it through the vent while driving and when I park after I get out. What could cause this? I have heard a couple potential problems.
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Terryg
June 27, 2012.



That smell is coming from one of the catalytic converters, typically from a misfire that dumps raw fuel into the exhaust system.

Caradiodoc
Jun 27, 2012.
Caradiodoc is right- can also be caused by leaking injector(s). If this is the case, it may not miss but may be hard to start, and will show a noticeable decrease in mpg.

DocDTC
Jun 27, 2012.