12 13 Carrying Out Engine Cleaning (N54, N53, N43)
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2010 BMW 335xi, 2010 BMW 335i, 2009 BMW 335xi, 2009 BMW 335i, and 2008 BMW 335xi. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
When cleaning the engine, it is absolutely essential to keep the ignition coil covers fitted in order to protect the injectors.