Mazda 2.2 D Engine inspection with broken oil pump chain, why it happened? P0524.

The engine I’m working on is an old Mazda 2.2 skyactive diesel Introduced in 2012 and manufactured without any modifications until 2013, mileage 180 K km. The error code P0524 note here that the DTC does not always indicate a broken oil pump chain, which means many other solutions exist.