We have heard from several owners of various Volkswagens fitted with the ACT technology who have experienced the same thing, although there does not appear to be an obvious solution.

We would suggest checking the actuator rod at the back of the engine which can work loose and cause the rattling noise to occur in two-cylinder mode as well as the gearbox actuator cables which can rattle against the exhaust heat shield. The issue may be occurring because in two-cylinder mode the engine is running less smoothly and causing components to vibrate when they do not in four-cylinder mode.