In a method for diagnosing an internal combustion engine having first and second fuel injectors, if a misfire is detected, the following steps are performed in sequence: a first fuel quantity of the fuel is introduced only by the first fuel injector; a check is performed to determine whether a misfire results from the introduction of a first fuel quantity in the first step; a second fuel quantity of the fuel is introduced only by the second fuel injector; a check is performed to determine whether a misfire results from the introduction of the second fuel quantity in the third step; and an engine error is diagnosed if a misfire was detected in the second or in the fourth step.