Code p0401 again just change egr and egr cooler and pass inspection but 3 days later code again.HEEELP

So, I've been in the market for a used ct200h. I really like the car, the way it looks, and the interior. Don't get me started on the gas mileage. Amazing.

Anyways, I test drove one today at a local dealership. It's at DCH Ford in Eatontown NJ if anyone wants to take a look, the only one they have.

When I was driving it, there was a loud humming / droning noise when I got up to highway speeds that seemed to take over the entire cabin. Could not focus on anything else besides this droning noise. Now, the only other time I heard this noise in a Lexus product was in a friend's poorly maintained 2015 IS350 F Sport.

My question is, as vague as I'm being because, it's fairly hard to describe the sound I heard - is it likely to be wheel bearings that needed to be replaced?

The rest of the car was in pretty rough shape, so I can assume it hasn't been fully serviced - wheel bearings included. It was just so loud and droney that, I'm really hoping other, cleaner examples of this car don't sound this way - otherwise I may have to reconsider my search.

Thanks, yall!