Mercedes-Benz W166 ML350 Bluetec NOx sensors replacement P229F CEL

I got a CEL with code P229F and there was a lot of white smoke and strong ammonia smell. The CEL means one of the NOx sensors were bad so I decided to replace both front and back. After replacing the sensors they had to be re-calibrated. I tried an independent mechanic but their scanner could not do it. The local Mercedes-Benz dealer did a software update and also re-calibrated the sensors. They also said the car is reporting P205C so I have to replace the Adblue pre-heater. I will be replacing that soon.