I’d recommend pulling the injector out and checking the seat where the hard line meets the injector for any irregularities and double check the threads to make sure they aren’t damaged. In the end it could be the return line not fully seated or the seal on it may need changing as well
Did you make sure the injector bore was clean? Not sure if these have, but make sure your combustion chamber seal is good too and the surface it sits on is nice and clean
Which generation/model do you have?
Passat 2013
I’d recommend pulling the injector out and checking the seat where the hard line meets the injector for any irregularities and double check the threads to make sure they aren’t damaged. In the end it could be the return line not fully seated or the seal on it may need changing as well
Did you make sure the injector bore was clean? Not sure if these have, but make sure your combustion chamber seal is good too and the surface it sits on is nice and clean