The KE-Motronic system features a fault memory that encompasses both the fuel injection and ignition systems. To check lambda control, connect a digital multimeter to the differential pressure regulator, let the engine idle for two minutes at normal operating temperature, note the control current, then disconnect hose 1 to observe an increase in control current. If there is no change, 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 start enrichment, connect a digital multimeter to the differential pressure regulator, disconnect the ignition coil power stage wiring, remove fuse 13, operate the starter, and ensure the control current drops to 35 to 45 A for a maximum of three seconds before returning to zero. To test overrun cut-off, connect a digital multimeter to the differential pressure regulator, switch on the ignition, note the control current, start the engine and increase the speed to over 3000 rpm, then quickly close the throttle to check for a brief negative indication in control current. For the cold start valve, disconnect the ignition coil power stage wiring, disconnect the temperature sender wiring and connect a 15 kilohm resistance in series, remove the cold start valve and check for an even 'cone' spray pattern for about eight seconds when the starter is operated, ensure the valve remains dry for at least a minute, and finally, check the valve terminals with an ohmmeter for a reading of 10 ohms. Special test leads are necessary for testing throttle valve switches, and this task is recommended to be performed by an Audi dealer.