Detonation (Engine Knock)

WARNING: This page does not describe the selected car, but rather 34 other vehicles, including the 2001 BMW Z8, 2001 BMW Z3, 2001 BMW X5, 2001 BMW M5, and 2001 BMW M3. However, it is still accessible from the selected car via links, so may be relevant.

Ignition timing too far advanced.
Blown head gasket.
Stuck thermostat (engine overheating).
Lean fuel mixture.
DME/Motronic control unit malfunction.
No coolant in radiator/engine (engine overheating).
Wrong octane fuel.