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.