As part of my final 100k service on the GTI having changed the cam chain, adjuster and tensioner last week...... I changed the primary and secondary Lambda sensors as they tend to slow with age if not come close to end of life.
Got BOSCH items from Opie Oils as they are the same as genuine ones (also made by BOSCH) but a lot cheaper at £110 for both.
She should be good now for another 100k......touch wood