funny smell

[GMC Sierra]

so the other day i noticed my truck smells like sulfur when its running my buddy told me it could be a problem with my cats, its an 04 and i wouldn't think my cats would be shot already plus isn't the 02 sensor behind the cats. shouldn't it throw a code? just wondering if its the problem or not

[1989K1500]

Did it idle for a long time? Mine smells like cat sometimes if it idles for a while.

[GMC Sierra]

probably only a couple of minutes not long at all just ran inside my gf's house to pick her up and then i smelt it

[96thebossgrnchv]

i had a funny smell and wondered wtf, then i looked and found that i hit some plastic or something and it melted all over one of my down pipes