Hello Saabgemeinde My problem is an annoying whistle noise which recently appears more and more often with cold engine and cold outside temperature during the departure phases. It sounds similar to a blow-off valve, which then disappears however with warm engine. As it sounds comes the noise in driving direction seen from the front left. have already looked all hoses and also changed the bypass valve, but unfortunately without success. Where could be the cause and wi e could one fix these ? Thank you in advance . Greetings Gary