Method for controlling the temperature of a glow plug

The invention relates to a method for controlling the temperature of a glow plug (1), wherein a setpoint temperature (Tset) is used to determine a setpoint value (Rset) of a temperature-dependent electric variable and an effective voltage (Ueff) which is generated by pulse width modulation is applied to the glow plug (1) and is used as correcting variable. According to the invention, it is provided that a mathematical model (4) is used to calculate an expected value (Re) of the electric variable, the electric variable is measured, a first error signal e1(t) is generated by evaluating the calculated value (Re), a value calculated from the effective voltage (Ueff) and the error signal (e1(t)) is used as the input variable of the mathematical model (4), wherein the mathematical model (4) uses the input variable to calculate an output variable (X) which defines the expected value (Re) of the electric variable, and wherein the output variable (X) of the mathematical model (4) is used to calculate a corrected value for the effective voltage (Ueff) and the effective voltage (Ueff) is changed to the corrected value.