The KE 111-Jetronic system features a fault memory that encompasses both the fuel injection and ignition systems. To check the lambda control, connect a digital multimeter to the differential pressure regulator, let the engine idle for two minutes at normal operating temperature, and observe the control current. After removing the dipstick, if the control current does not increase, disconnect the lambda probe wires and ground the green wire for about twenty seconds; a change in control current indicates a faulty lambda probe. For cold acceleration enrichment, disconnect the temperature sender wiring plug and connect a digital potentiometer with a resistance of 3 kilohms, such as the VAG digital potentiometer 1630. While running the engine at idle, note the control current and quickly open and close the throttle valves, ensuring the control current briefly rises to at least 6 mA. To test the cold start valve, remove it and hold it over a measuring beaker, then operate the starter to check for an even 'cone' spray pattern for two to three seconds. After wiping the valve dry, confirm it remains dry for at least a minute. The throttle valve switches monitor the closed and fully-open positions of the throttle, requiring special test leads for testing, which is best performed by an Audi dealer. For the diaphragm pressure switch, additional details can be found in the relevant sections.