Abstract: A method for monitoring the enabling of a system which is assigned to an internal combustion engine, in which the readiness for operation of the system is dependent on an operating temperature, is characterized in that a fault in the enabling of the system is inferred (106) if operation of the system cannot be detected on expiry of a predeterminable time period after the starting of the internal combustion engine or on the recurrence of readiness for operation.

Abstract: A method for operating an internal combustion engine in a catalytic converter heating operation, the internal combustion engine being able to be operated in a normal operation, including the following steps: ascertaining a first exhaust gas temperature reading, which gives the exhaust gas temperature of the exhaust gas in a first catalytic converter, particularly in an oxidation catalytic converter; operating the internal combustion engine in a first operating mode, in which, in contrast to the normal operation, the exhaust gas, having an increased exhaust gas temperature, is exhausted from at least one cylinder of the internal combustion engine, as long as the first exhaust gas temperature reading has not reached a specified first temperature threshold value. This method enables a robust and simple diagnosis of the effectiveness of the catalytic converter heating operation according to the requirements of CARE Title 13 CCR Section 1968.2 Chapter.

Abstract: A method for monitoring the enabling of a system which is assigned to an internal combustion engine, in which the readiness for operation of the system is dependent on an operating temperature, is characterized in that a fault in the enabling of the system is inferred (106) if operation of the system cannot be detected on expiry of a predeterminable time period after the starting of the internal combustion engine or on the recurrence of readiness for operation.

Abstract: A method and a device for diagnosing an ascertainment of a performance quantity of an internal combustion engine. Within the scope of a first diagnostic process a first value which is characteristic of a first performance quantity of the internal combustion engine ascertained at a first point in time after switching off the internal combustion engine is compared to a predefined value, and an error is identified when in the comparison it is detected that the absolute value of a first difference between the first value and the predefined value exceeds a predefined first threshold value for the first point in time. The predefined first threshold value is predefined to be smaller the longer the time since the internal combustion engine has been switched off.

Abstract: The invention relates to a method for checking the operability of an exhaust gas after-treatment system (12) of an internal combustion engine by evaluating signals (S—22, S—26) of a first exhaust gas sensor (22) and a second exhaust gas sensor (S—26), between which a catalyst 24 is disposed. The method is characterized in that the air ratio L of an exhaust gas atmosphere flowing through the exhaust gas after-treatment system (12) is reduced from a first lambda value 11>1 to a third lambda value L3 with L2>L3 via a second lambda value L2 with L1>L2>1, the value of a time duration (dt—26; dt—22) is detected, which is between the times (t5, t6, 7t7, t8) at which the signals (S—26, S—22) of the two exhaust gas sensors (22, 26) display the second value L2, the value of the time duration (dt—26; dt—22) is compared to a threshold value (dt_max), and an analysis of the operability of the catalyst (24) is not carried out if the value of the time duration (dt—26; dt—22) is greater than the threshold value.

Abstract: A method and a device for diagnosing an ascertainment of a performance quantity of an internal combustion engine. Within the scope of a first diagnostic process a first value which is characteristic of a first performance quantity of the internal combustion engine ascertained at a first point in time after switching off the internal combustion engine is compared to a predefined value, and an error is identified when in the comparison it is detected that the absolute value of a first difference between the first value and the predefined value exceeds a predefined first threshold value for the first point in time. The predefined first threshold value is predefined to be smaller the longer the time since the internal combustion engine has been switched off.