Abstract: A method for determining the temperature of a sheathed-element glow plug during operation in an internal combustion engine is described, in which a temperature-resistance reference correlation is determined. In order to reduce the tolerance range of a sheathed-element glow plug, after the sheathed-element glow plug has been installed in the internal combustion engine, a calibration step is carried out in which, with the aid of the temperature-resistance reference correlation determined prior to the installation of the sheathed-element glow plug in the internal combustion engine, a temperature-resistance correlation specific to the sheathed-element glow plug is ascertained, from which the temperature of the sheathed-element glow plug during operation of the sheathed-element glow plug in the internal combustion engine is determined.

Abstract: A method is described for ascertaining a surface temperature of a sheathed element glow plug in an internal combustion engine, in which a physical parameter is utilized for ascertaining the surface temperature. In order to be able to ascertain a precise surface temperature at a reduced outlay in terms of computation and development, at least two physical parameters of only the sheathed element glow plug are used for ascertaining the surface temperature of the sheathed element glow plug.

Abstract: In a method for detecting a replacement of sheathed-element glow plugs in an internal combustion engine, an electrical parameter of the sheathed-element glow plug is determined during a driving cycle and is compared with a stored value of the same electrical parameter of the sheathed-element glow plug that was determined in a preceding driving cycle. In the driving cycle, the same electrical parameter is determined for all sheathed-element glow plugs installed in the internal combustion engine, and the determined pattern of the electrical parameter is compared with a pattern that was ascertained in a preceding driving cycle, a replacement of a sheathed-element glow plug being detected if the pattern of the driving cycle deviates from a pattern of the preceding driving cycle.

Abstract: A method for determining the temperature of a sheathed-element glow plug during operation in an internal combustion engine is described, in which a temperature-resistance reference correlation is determined. In order to reduce the tolerance range of a sheathed-element glow plug, after the sheathed-element glow plug has been installed in the internal combustion engine, a calibration step is carried out in which, with the aid of the temperature-resistance reference correlation determined prior to the installation of the sheathed-element glow plug in the internal combustion engine, a temperature-resistance correlation specific to the sheathed-element glow plug is ascertained, from which the temperature of the sheathed-element glow plug during operation of the sheathed-element glow plug in the internal combustion engine is determined.

Abstract: In a method for detecting a replacement of sheathed-element glow plugs in an internal combustion engine, an electrical parameter of the sheathed-element glow plug is determined during a driving cycle and is compared with a stored value of the same electrical parameter of the sheathed-element glow plug that was determined in a preceding driving cycle. In the driving cycle, the same electrical parameter is determined for all sheathed-element glow plugs installed in the internal combustion engine, and the determined pattern of the electrical parameter is compared with a pattern that was ascertained in a preceding driving cycle, a replacement of a sheathed-element glow plug being detected if the pattern of the driving cycle deviates from a pattern of the preceding driving cycle.

Abstract: A method and a device for monitoring a fuel injection system are described. A manipulated variable is modified by a certain amount. A first value of a measured variable is detected prior to the modification and at least a second value is detected after the modification. An error is detected when the first value and/or the at least second value deviate from an expected value.

Abstract: A method and a device for monitoring a fuel injection system are described. A manipulated variable is modified by a certain amount. A first value of a measured variable is detected prior to the modification and at least a second value is detected after the modification. An error is detected when the first value and/or the at least second value deviate from an expected value.