Abstract: The invention provides a method for detecting the improper interchanged installation of left and right lambda probes in an internal-combustion engine having two cylinder banks, each of which has an exhaust gas catalyst with a lambda probe and a lambda control unit assigned thereto, and whose injection valves can be switched off at least by cylinder bank. The injection valves of one of the two cylinder banks are switched off at least for a time which corresponds to the reaction time or change-over time of the lambda probes. The signal from the lambda probe assigned to the switched-off cylinder bank is then compared with a predetermined threshold value at the end of the switch-off time of the injection valves. An incorrect connection of the lambda probes is detected when the lambda probe signal exceeds or falls below the threshold value.