Have Volkswagen Questions? Ask an Expert Now.
have you checked the oil level?
it is odd that they replaced the turbo bypass, since it doesn't normally fail anymore. The old early design yes,not this one. I think maybe you have an issue with the crankcase vent/ oil separator, and it is causing oil to go into the intake tubes (which will make it show up in the area of the bypass valve as it seeps out the fittings there)
Try taking the oil cap off with the engine running, if it sucks down really hard and is impossible to remove I would think of that as confirmation that the pcv is the issue
It is possible- but since the dealer just did an oil change, you might want to bring it back to them and point it out. It's possible they may have put the wrong filter on it, or lost the insert spring that sits under the filter, and it is not holding pressure like it should.
It's also possible that it is setting a stored fault, but not turning on the CEL since it is not happening all the time.