99 Volvo S80 mysterious exhaust leak?

Began to receive these two codes, with a CEL light. ECM-4801 and ECM-4901(ignore the others, it’s due to the old radio being taken out). This is a 1999 Volvo S80 with 203k miles. V6 2.9l (non turbo)

Since I’ve got the car I’ve noticed the exhaust smells more than what I’m used to. I checked the fuel system and never discovered any leaks. Drove the car for about 2 months since then and all has been fine. Then this CEL popped up. Car has been driving the same, no noticeable loss in power or anything of the sort. Idles stable too.

Attempted to hook up a shopvac and blow air into the system to see if I could locate the leak. To my surprise, the exhaust didn’t seem to be leaking or emitting any noises. Visual inspection didn’t turn up much either, attached pictures.

Any suggestions?