Audi S8 Oil Pressure Crisis: Knocking Engine Alert

I had a very similar issue with my 2002 Audi A8 4.2L. As someone with some experience working on these engines, the symptoms you describe match exactly what I encountered. The oil pressure warning and engine knocking turned out to be a failing oil pump in my case. The repair cost was 755 Euro including parts and labor. The workshop diagnosed it using proper pressure testing equipment, as oil pressure sensor readings alone can sometimes be misleading. The repair involved: Removing oil pan, Replacing the complete oil pump assembly, New gaskets and seals, Oil and filter change The engine knocking sound you mention is particularly concerning, as continued low oil pressure can severely damage engine bearings. Time is critical here to prevent more extensive engine damage. To help provide more specific guidance: What oil viscosity are you currently using? Has the car displayed any other warning lights? How many miles/kilometers are on the engine? Have you noticed any oil consumption issues? My recommendation would be to avoid driving the car until properly diagnosed, as oil pump failure can lead to catastrophic engine damage very quickly.

Last service was at 114000 KM, just 735 KM ago. After reading your detailed response, I checked for oil leakage around the pan and found some wet spots. The mechanic used 5W-40 oil during the last service. The car runs fine at higher RPMs, but the low oil pressure warning appears mainly at idle. The bearing wear symptoms you describe match my situation exactly. There are no other warning lights, but the knocking gets worse when the engine is warm. Given the oil pump repair cost you mentioned at 755 Euro, this seems like a reasonable fix to investigate first before risking more serious engine damage. Will schedule pressure testing this week to confirm if its the oil pump or possibly the oil pressure sensor giving false readings.

Thanks for the additional details about your S8. The wet spots around the oil pan match what I experienced before my repair, its often a sign the pan gasket is leaking, which can contribute to pressure loss. The fact that your pressure warning mainly occurs at idle but improves at higher RPMs is another classic symptom of oil pump failure. My car showed the exact same behavior before the repair. The 5W-40 oil viscosity is correct for these engines, so thats not likely the source of your issue. After my oil pump replacement, I learned these engines can develop bearing wear quite quickly once oil pressure drops. The knocking getting worse with heat suggests the bearings may already be affected. My total repair ended up around 755 Euro because we caught it early, but costs can multiply fast if bearing damage occurs. Since youre only 735km past your last service, its worth getting the pressure tested ASAP. On my A8, the workshop confirmed low oil pressure using their diagnostic equipment, the readings were well below spec at idle but somewhat better at higher RPMs, exactly like youre describing. The oil pressure sensor is a cheaper potential fix, but given the knocking sounds and wet spots, an oil pump failure seems more likely based on my experience with the same engine.

Thanks for clarifying the oil viscosity and mileage details. After hearing about your successful oil pump repair at 755 Euro, Im convinced to have this checked immediately. The matching symptoms of oil pressure warnings at idle and knocking sounds when warm are too similar to ignore. Found those wet spots near the oil pan during my inspection, which really confirms what you experienced. The 5W-40 oil is indeed correct for these engines, so no issues there. Your experience with the oil pump failure showing similar behavior, worse at idle, better at higher RPMs, matches my situation perfectly. The workshop visit is scheduled for tomorrow morning. Will have them do proper oil pressure testing first before assuming anything, but your repair experience gives me a good baseline for what to expect. Really hoping to catch this early enough to prevent major bearing damage, as you suggested. Appreciate the detailed breakdown of your repair process and the heads up about potential bearing wear. Will update once I get the pressure test results and confirm if its the oil pump or just the pressure sensor.