Awful smell

My sister’s 2004 Acura TSX has an odor that she, her husband and their mechanic cannot explain. Apparently it smells like something might have crawled in the engine and died! It seems to be strongest near the battery and near the front grill. The mechanic looked at the air filter, the battery, the exhaust and other visible places to see if a rodent had died there. No luck. It’s driving them crazy. Any suggestions?

Perhaps something got between the plastic fender liner and the fender and died there. A mouse could easily find a small opening and get in. A dead mouse is very small and hard to see. Keep looking, you’ll find it.

It was a bird. Problem solved.