A shop will charge something to tell you which is bad but will probably replace both fronts or both rears or all of them...and you will pay
for it....but the diagnosis was free...supposedly...lol lol
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1. get a second opinion at Oreilly's and Advance for confirmation and to see if one store has a better scan tool that pinpoints which one.
2. at home swap the front two sensors side to side, see if the readings change.
3. swap the two rear sensors, see if the readings change.
4. that might tell you if a sensor is bad and where..but no guarantee.

5. clean sensors well when you have them out in case crud could cause a code. If code goes away, maybe cleaning was all that was needed.
OR
6. see if the sensors are identical or different front to rear, have excess wear, discoloration, etc. or any other difference.
Probably VW uses the same sensor at all positions to save inventory costs.
Length of wire difference will also indicate a front to rear difference. Logically they will be the same side to side,
but not front to rear since the front wheels steer, the rears don't steer.

6a. have one of the stores look up the front sensor part number and the rear sensor part number to see if they are the same number,
that confirms that all are identical at least front to rear....which also means logically they are probably identical side to side.
You will need to know the price and part number anyway.

You could also inquire on the internet as if you were thinking about adding to your cart,
and if you were buying, they would list the part number.....for you to see if they are the same or different numbers.
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I usually check the internet part numbers so I don't take up the parts guys time.
When I buy, I buy from the guy who was most helpful to me. They took their time to help me, and buying at that same store from that same guy
is a way of saying thanks, and sets up a good relationship for the next time you need help with something.
Some of those guys know things about cars, and I may need help again sometime.

I don't mind paying a little extra if needed, since I sorta paid to learn from the most helpful guy....and I write down his name for next time.
And I go to that store next time.....and next time, my opening sentence is " (name) I want to thank you for helping me last time with------fill it in-----------,
but I have a question for this time..." Maybe take him a 6-pack of soda when you say thanks. Showing appreciation counts these days.
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I prefer new parts with the same brand, same kind of box and no grease/dirt from the last jerk who returned a part.
I don't accept parts that someone has messed with. I don't accept one in a German box and another in a Japanese box from a different manufacturer.
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OR
7. now that you have experience removing and replacing, hit the junkyard u-pull it and buy all 4 sensors from an identical car. Mark which is which..RR RF LR LF
8. one by one, replace the cleaned sensors and drive it a few miles to reset them with the computer, and see if the light goes out. WHEN THE LIGHT GOES OUT YOU FOUND THE BAD ONE. If you didn't find it one of my other suggested ways.
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I replace new front or rear sensors in pairs in case there is a wear difference and I want my brakes to WORK when I hit the pedal.
I clean and ziplock leftover GOOD parts, write on the bag what they are, and keep them for next time or they go as spares when I sell the car.
Your car sells quicker when you give them clean spare parts.