bbqn

Good advice. The PCV was the first thing I checked. Pulled air box off and checked all lines and connections. All good. In my case, I can feel the exhaust coming out of the connection between the manifold and y-pipe. Bolts are tight. May try J-B weld 37903 before taking it apart.

Same problem. 2018 Sierra 5.3, 60k. Smells like rich exhaust coming thru vents when stopped. Under the hood also. Exhaust at the tailpipe does not smell like this. So I figured it must be before the cats. Digging around I found an exhaust leak on pass side where manifold attaches to y pipe. This is where that seal Kevin mentioned above is located. That small seal may not fill the void where I feel exhaust coming out. Also, I found a good size dent in the y pipe from a chunk of steel I hit that a truck kicked up. My flange may be bent. Time to take it apart and see what's going on.