So, I got a CEL this weekend. Code came back as my B1S1 O2 was stuck lean. I was confused since I thought this was the O2 in the turbo, not the DP. So, I scoot my fat ass under the car to take a look-see. I checked the turbo from underneath and couldn't see anything. Then, I noticed the O2 sensor in the DP was contacting a black bar that kinda looks like a sway bar (I thought the sway bar was in front of the engine?). Anyway, upon closer inspection, it became clear that the contact between the sensor and the bar had conducted the vibrations down to the welds on the bung, which were now split open. That explains the lean code...

Now, I have to get it welded back up (with a little clearance this time) and hope for the best. Still confused as why this O2 would be B1S1 when there's one in the turbo housing.?.?.? Oh well, just a heads up.

PS - I don't remember the brand of DP as I bought it used from a friend. But, I do know it was one of the first ones out. Point is, check under your car if you have a catless DP to make sure nothing is contacting that O2 sensor.