Proposed is a method for monitoring a passive pressure limiting valve (11) via which fuel is discharged from the rail (6) of a common rail system into the fuel tank (2), in which method, upon the detection of a defective rail pressure sensor (9), a switch is made from a rail pressure regulation mode into an emergency mode, wherein in the emergency mode, the rail pressure is successively increased until the pressure limiting valve (11) reacts, in which method, in the emergency mode, the pressure limiting valve (11) is set as open when the starting phase of the internal combustion engine has additionally been detected as having ended, and in which method, in addition, the opening duration of the pressure limiting valve (11) is monitored.