Now that im thinking about this, I looked at some exhaust schematics using google images.
Even though this thread is old and people are talking about a p2002 code im thinking the reason why its triggering the p2002 is because the flex pipe has broke and is causing an exhaust leak. You might be able to check the flex pipe for any black color (Soot) There is an Exhaust throttle valve that closes which i assume has to do with regen reasons. The valve closes when its time to regen, and helps pick the DPF temp up in order to burn the soot through the filter. While the arrow pointing to the EGR filter is marked, behind the EGR filter pipe that runs and taps in just above the "Unmarked" flex pipe there is also a sensor right next to the EGR inlet at the bottom of the DPF Filter but before the flex pipe. On top of the filter you have a Wide Band Nox sensor as well, i assume both are used to regulate pressure and temp for emissions and regens. There's really no other reason why there would be an exhaust throttle valve for a diesel car unless it has to do with creating a closed loop in order to bring temps and pressure up to cook soot out of the dpf filter.
When i drove semi trucks, every 350k miles on a Peterbilt 579 (2010-up), the flex pipe would rot out and break. Their design was poor, trucks would refuse to do regens and would announce engine derate fault messages in the dash. Flex pipes were common points of failure on those trucks. If the truck did do a regen on a broken flex pipe the cab would fill up with white smoke, sound like a flightier jet taking off and choke you out from burning DEF fluid.
Where im getting at with this very long message and what makes sense to me, The dealer ship tells you, that you now need a new DPF filter, while i decided to ebay check and see of any replacement filters. I found several for my 2009 Jetta TDI, and noticed the flex pipe is factory placed on the DPF filter. So instead of dealership just cutting a bad flex pipe off and welding a new one. They just recommend or tell you that "You need a new dpf filter" because at that point, all they have to do is undo the bolts, connectors, v bands, and slip the new one on in less than 30 minutes and charge you more money.
I might be entirely wrong about this, but this based on my theory's and doing research on these TDI parts.
Here is an image i found off of ebay, you can see what im talking about. I am seeing Black soot at the top of the flex pipe where the chances of it leaking and snapping are most possible.
Edit - While P2002 code says "Particulate Trap Efficiency below threshold 1" As far as i know, im not sure if 1 means the bottom sensor or the top. But if the statement says "Below Efficiency" That is telling me there is a leak somewhere and the most common part to cause a leak on any exhaust system is a flex pipe.
go to google and type "p2002 vw tdi"
and the response says the following.
Error Code
P2002 is defined as Diesel Particulate Filter Efficiency below Threshold Bank 1, which refers to an issue in the efficiency of the particulate filter in the exhaust, which is most likely caused by faulty filter or sensor, or "Exhaust Leak".
Why im leaning more towards an exhaust leak is because this is common, this area of the part still sustains a lot of heat, the moves a lot because of engine and suspension, and can depend on where you live and if the roads get salt every single winter, this can cause pipes to corrode and rot out and become weak.
