I bought my 2012 last May, and on my first long trip, the CEL light came on. I ordered a Ross-Tech cable, and discovered, I too, have implausable values coming from the Nox sensor.
Clearing the code, the car will run for 200 to 400 miles before throwing the code again.
Recently I followed the advise from the Ross-Tech's forum's thread regarding the subject, which involved removing the Nox sensor and cleaning it. The author spoke of cleaning it with oven cleaner and burning off contaminates with a torch.
link
http://forums.ross-tech.com/showthread.php?2617-2012-VW-Passat-Adblue-reset/page4
Around a week ago, I took an expedition under the damn car, to harvest one Nox sensor. Being distracted with unexpected company that showed up, I did a half ass job cleaning the sensor, only using a torch on it. I might add the damn thing looked very clean.
I reassembled the car. The following week i drove 300 miles into a trip, and CEL did come on again, but this time the Adblue count down proceeded as well.
Since VW won't fix the thing on emission warranty, I plan to remove it again, and try the oven cleaner, torch, and compressed air steps outlined on the other forum. I'm also going to remove the adblue nozzle on the tail pipe, to be sure its clean.
I'll be sure to post my findings.
Btw, I looked around on line and the Nox sensor assy was available for around $375.00, but I'm trying to avoid that if possible.
