A first camshaft misalignment value is determined from a measurement variable allocated to an engine air flow path. A second misalignment value is determined from a first operating variable outside of the air flow path. A trouble-free operation is identified when both values are smaller than a predefined first threshold. Misalignment is confirmed when one of both values is greater than the first and a difference between both values is smaller than a predefined second threshold. An air flow path fault is identified when the first value is greater and the second value is smaller than the first threshold and when the difference between both values is greater than the second threshold. A fault outside of the air flow path is identified, when the second value is greater and the first value is smaller than the first threshold and when the difference is greater than the second threshold.