In a method for operating an internal combustion engine, a first data quantity is derived based on a signal of a first sensor which detects the pressure in a first combustion chamber of a plurality of combustion chambers, and a second data quantity is derived based on a signal of a second sensor, which second data quantity is a function of the pressure variation in at least one of the plurality of combustion chambers. The first data quantity and the second data quantity are functions of the pressure variation in the same combustion chamber, and a drift of the second sensor is ascertained from a change over time in the second data quantity with respect to the first data quantity.