I had to replace the connector to the exhaust for the flap just before the flap malfunctioned. It was replaced with the extended warranty for "the fix". It sounded like a chain bouncing and jingling while driving down the road. Interesting way to hear how it works.The exhaust regulation flap. It has a couple functions, one of them is for the low pressure EGR. It also can work during certain regen functions. If you google "commonrail TDI self study guide" you can view a .pdf that better explains its function.