In method for operating a magnetic resonance apparatus that has a gradient power amplifier that supplies a voltage to a gradient coil, and a gradient power amplifier control processor that provides control a control signal thereto that predetermines the aforementioned voltage, and a simulation computer that models an operational characteristic of each of the gradient coil the gradient power amplifier, an actual current value of a current fed into the gradient coil by the gradient power amplifier is measured and a target current value of the current fed into the gradient coil by the gradient power amplifier is determined by the simulation computer, using the control signal as an input variable. A fault signal is generated as a function of a determined deviation in the actual current value from the target current value.