DME 7.8 DME 7.8 0 · 0-122.9P1155

DME 7.8 DME 7.8 0 0-122.9P1155 Oxygen Sensor Ahead of TWC, Bank 2 – Above Limit Diagnosis conditions Note! A lot of time is required (several days) until a fault is detected. Possible fault cause ♦Valve lift fault ♦False air on the oxygen sensor after TWC ♦Oxygen sensor Affected terminals - Note! ♦As this fault can be caused by a faulty flat-base tappet, a system test for a small lift has to be performed initially. The fault can occur sporadically; the test should therefore be performed at least three times when the engine is at operating temperature. ♦First indication of a valve lift fault can be provided by the adapta- tion values at idle speed (RKAT) and in the lower part load (FRAU) if they differ by more than 10 %. Perform system test for small lift Warning! Test is carried out while driving. Have a second person oper- ate the Porsche System Tester 2. During the system test for small lift, the valves remain at small lift, regardless of the type of driving. Faulty switching conditions can be detected by rough running, just like with misfire detection. Several cylinders may be stored as faulty, although only one valve on one cylinder is faulty. In order to ensure that the fault is repaired, the flat-base tappets of the inlet valves of the entire cylinder bank should be replaced if a fault occurs. 2469 P1155 0-122.9 page 1 Printed in Germany – 6, 2002 p1155