Abstract: In order to check the functional capability of a three-way catalytic converter of a lambda-controlled internal-combustion engine, the efficiency of the catalytic converter is determined in a conventional way by determining the oxygen storage capability of the catalytic converter. In order to be able to adjust the efficiency with regard to temperature changes, a substitute value for the temperature in the catalytic converter is calculated. Using this substitute value, the efficiency, which has been determined for the catalytic converter, is adjusted for temperature influences. The measure of the functional capability of the catalytic converter thus obtained is accurate even after non-steady-state operating phases of the internal-combustion engine when the catalytic converter is not yet isothermal.

Abstract: A method for monitoring functional capability of a tank venting system for a motor vehicle, includes evacuation of the tank venting system through the use of negative pressure or vacuum prevailing in the suction tube of an internal combustion engine and assessing the system based on negative pressure buildup and negative pressure letup gradients. Additionally, besides other abnormal termination criteria, the dynamics of pressure changes are also monitored and the method is immediately discontinued, if pressure fluctuations are ascertained which exceed a predetermined measure.

Abstract: A method for recognizing stretches of rough or bad road includes recognizing tank pressure values at successive evaluation instants. A change in tank pressure is ascertained from successive tank pressure values. A stretch of rough or bad road is recognized if the change exceeds a limit value.

Abstract: A tank venting system for trapping fuel vapors and feeding the fuel vapors to an internal combustion engine having a fuel tank and an intake tube, includes a container adsorbing fuel vapors. A venting line is connected between the fuel tank and the container. A regeneration line is connected between the container and the intake tube of the internal combustion engine. A ventilation line communicates with the atmosphere and the container. A ventilation valve closes the ventilation line. A tank venting valve is disposed in the regeneration line and is triggered in an opening direction for feeding fuel vapors stored in the container. A pressure sensor detects a system pressure of the tank venting system. A method for monitoring the tank venting system includes monitoring the system pressure with the pressure sensor during the feeding of the fuel vapors, categorizing the ventilation valve as functioning improperly if a predetermined pressure threshold value is exceeded, and closing the tank venting valve.