x5 35d SES codes - NOx sensor

[IronRobi]

2011 x5 35d with 165,000km

A new Shell station opened in our area and was the first to carry their V-Power diesel. A few weeks back the wife headed out and filled up using the v-power for the first time. She called me before leaving the parking lot because as soon as she started moving, the SES light came on.

My first instinct because of the timing was something fuel related, but when I pulled the codes it was all NOx sensor related. Burned through that tank as quick as possible anyways, cleared all the codes, they all ended up coming back. So the timing could have just been purely coincidental.

Here are the codes I'm pulling from Carly:
00475f - NOx sensor before DeNOx catalytic converter linear lambda or heating stop
00475e - NOx sensore before DeNOx catalytic converter linear lambda or heating stop
004bf5 - Too long invalid NOx sensor upstream of the DeNOx catalyst NOx signal
0046b9 - NOx sensor Nox filtered difference to the calculated NOx measurement signal too low before the DeNOx catalyst plausibility

I don't want to start throwing money at parts before knowing what's wrong. Looking at this I would think the place to start would be the upstream NOx sensor since all codes relate to before cat. Looking at some parts they seem to indicate left bank or right bank, but I've never heard of there being 2?

I'm mechanically inclined, have built many cars from the frame up, but not a diesel expert and there doesn't seem to be much out there on these specific codes. Looking for advise from those smarter than I.