I was getting the 202B fault with my Check Engine Light starting at 74k miles. I have a 2012 TDI SEL. Dealer quote was about $1200 to repair, so I figured I'd do it myself.
The part number is 561-198-970. You can get it online for the mid $400 range. I wasn't absolutely confident about my ability to do the job, so I paid a few bucks more for a return policy without a restocking fee. Here's what you get.
You will also need a torx driver and a socket wrench. You also need a hex bit. A siphon is helpful.
First step is to remove the bumper.
In each wheel well, there are 5 screws to remove. I used a torx bit with a 1/4 inch socket wrench to get in the narrow spots. It would be easier if you remove the wheels, but I didn't feel like jacking up the car. This picture was taken after removing the screws and prying the bumper away.
The top-most screw is at a tight angle
Then remove the tail-lights. Unsnap the electrical connector and unscrew the large white plastic screw. The whole assembly comes out easily.
Remove the two torx screws.
Next remove the torx screws from under the back of the bumper.
Then pry the cover off starting from each wheel well. It takes a little elbow grease, but all that's left holding the cover on are plastic clips.
Here's the Adblue tank with the cover off
There are 3 bolts holding the tank on. Two are located at the rear of the tank, and one in the front. Remove those and the tank comes right down.
Remove the foam piece and start disconnecting wires. You'll have to cut some cable ties to disconnect the mess. Don't worry, you can't reconnect the wires incorrectly later. Each clip is shaped differently. The kit comes with new wire clips also.
Now would be a good time to siphon out some of the Adblue fluid. You can use a fish tank vaccum for that (I wouldn't use it in a fish tank again though)
Now remove the three bolts holding the control module on.
Pull upwards. There is an O ring holding the module onto the tank, so you'll get some resistance.
Note the position of the arrow and the two hash marks on the tank. This will be important when putting everything back together.
Unscrew the large ring holding the heater down. Its very tight. I used a hammer and pry bar to loosen the ring. You get a new ring in the kit, so no worries.
Now pry off the top of the heater element. I used a flat head screwdriver. Remove the large O ring.
You have to rotate this piece a few degrees before it comes out.
Now that you have it off, its just the reverse to put it back together again. Beware of the arrow when you reseat the top of the heater. I made the expensive mistake of putting it the wrong place and broke the nipple off the control module ($500 retail, you can find it for $375). It also helps to have an empty Adblue tank, since it makes it lighter to reinstall on the frame.
Whole project should take less than an hour if you know what you're doing.