I just drove to the Alps from London in my 2016 T6 4motion. Before leaving I had a garage put in brighter bulbs and when taking out the air filter they saw it was dirty and replaced it. While en route my oil warning came on. I found the oil filler neck was loose and also realised that some oil had dropped onto the engine and while running fumes were escaping. I am guessing that the garage knocked it and it broke at the plastic weld. Could it have been caused by. gas pressure? It is very hard to find the part number. If anyone has a parts diagram of the filler assembly this would be v useful.