Lambda sensor recall?

[Svetty]

I recently took my 2014 2.0 TDI for it's first MOT. The dealer advised that it was due a Lambda sensor recall/replacement and carried out the work. Since then I am convinced that the economy is significantly less good although the car seems to run fine. Has any one else come across this?

I did telephone and ask if this was an emissions related issue - I was told not and that the running of the car isn't affected adversely......