A temperature sensor for detecting heating of at least one electrode pole of a temporarily or permanently implantable electrode line or a similar implant having at least one elongated electrical conductor which is connected to at least one electrode pole. The temperature sensor has an impedance detecting unit or is connected to one and is configured for evaluating an electrode pole impedance detected by the impedance detecting unit in such a manner that the evaluation takes place with respect to a temperature-dependent feature of the electrode impedance. The impedance detecting unit is electrically connected to the at least one electrode pole or is configured and arranged to be electrically connected to the at least one electrode pole.