Abstract: Described is a method for detecting a glow plug replacement of an engine, wherein a first value of a temperature-dependent variable is measured at a first glow plug of the engine and, simultaneously, a second value of the temperature-dependent variable is measured at a second glow plug of the engine. The first value of the temperature-dependent variable is compared with a stored reference value of the first glow plug and a glow plug replacement is detected if the difference of the first value from the reference value exceeds a threshold value. According to this disclosure, it is provided that the reference value is a value which, in an earlier measurement, was measured at the first glow plug simultaneously with the measurement of a value at the second glow plug which corresponds to the second value within a predefined tolerance.

Abstract: A method for operating a glow plug by means of pulse-width-modulated voltage pulses which are generated by controlling a load transistor, wherein a heating current flowing through the glow plug is measured and the duty cycle of the pulse-width-modulated voltage pulses is changed in accordance with values of the heating current. The heating current can be measured by means of a current measurement circuit, through which a sense current flows parallel to the load transistor, and the value of the heating current is calculated by multiplying a measured value of the sense current by a kILIS factor, wherein the temperature of the current measurement circuit is measured and the kILIS factor is defined in accordance with the measured circuit temperature. A glow plug control device is also disclosed.

Abstract: Described is a method for detecting a glow plug replacement of an engine, wherein a first value of a temperature-dependent variable is measured at a first glow plug of the engine and, simultaneously, a second value of the temperature-dependent variable is measured at a second glow plug of the engine. The first value of the temperature-dependent variable is compared with a stored reference value of the first glow plug and a glow plug replacement is detected if the difference of the first value from the reference value exceeds a threshold value. According to this disclosure, it is provided that the reference value is a value which, in an earlier measurement, was measured at the first glow plug simultaneously with the measurement of a value at the second glow plug which corresponds to the second value within a predefined tolerance.

Abstract: A method for operating a glow plug by means of pulse-width-modulated voltage pulses which are generated by controlling a load transistor, wherein a heating current flowing through the glow plug is measured and the duty cycle of the pulse-width-modulated voltage pulses is changed in accordance with values of the heating current. The heating current can be measured by means of a current measurement circuit, through which a sense current flows parallel to the load transistor, and the value of the heating current is calculated by multiplying a measured value of the sense current by a kILIS factor, wherein the temperature of the current measurement circuit is measured and the kILIS factor is defined in accordance with the measured circuit temperature. A glow plug control device is also disclosed.