Audi S4 Oil Warning Light May Be Just Bad Sensor

I had a similar sensor issue with my 2015 Audi S5, and I have some experience working with these common oil detection problems on VAG engines. The symptoms you describe match exactly what I encountered, persistent oil pressure warning despite the engine running smoothly. After initial concern about major engine problems, it turned out to be much simpler. In my case, the workshop diagnosed a faulty sensor connection, specifically a damaged wiring harness to the oil pressure sensor. The automotive oil monitoring system was getting incorrect readings due to this connection issue. They found the cable had slight wear causing intermittent contact. The fix involved replacing the wiring connector and ensuring proper connection to the sensor. Total cost was 95 Euro including diagnostic time and parts. It has been working flawlessly since the repair. Before suggesting specific solutions, could you share: Current mileage on your S4, Whether the warning light is constant or intermittent, If you notice any engine oil consumption, When the issue first started, Whether any recent work was done near the engine oil system This information would help determine if your case is similar to what I experienced or if it might be a different underlying issue.

Thanks for sharing your experience. My last service was just 2000 KM ago, and that makes the current mileage 157885 KM. The warning light started appearing intermittently about a week ago, but now its constant. The oil level is fine according to both the dipstick and electronic readings. The timing of this issue is interesting since no recent work was done near the oil system components. Given your similar experience with the faulty sensor connection, I will have the mechanic check the wiring harness first. It sounds like a sensible starting point before replacing the entire oil pressure sensor assembly. In my case, there is zero unusual oil consumption between changes, and the engine runs perfectly smooth with normal operating temperatures. This matches what you mentioned about it likely being an oil signal issue rather than an actual oil pressure problem.

Thanks for the additional details. This further confirms my initial thoughts about the sensor connection, especially since your symptoms mirror what I experienced. The fact that the warning started intermittently before becoming constant is a classic sign of wiring harness issues in these VAG oil monitoring systems. One key point from my experience, the car maintenance records showed these sensor issues often develop around the 150000 KM mark, which aligns with your mileage. The oil pressure sensor wiring tends to degrade due to engine heat cycles over time. What worked in my repair was having the mechanic perform a complete diagnostic of the oil sensor circuit. They found that while the sensor itself was functioning, the signal was getting corrupted due to the worn wiring, exactly the same pattern youre describing with the working engine but constant warning light. Since your engine performance and oil consumption are normal, this strengthens the case for an electrical rather than mechanical issue. The repair should be straightforward and relatively inexpensive, likely in the 100-150 Euro range if its the same wiring harness problem. Just ensure the workshop does a full system scan before and after the repair to confirm the fix resolved all stored error codes in the oil monitoring system.

Based on your detailed response and my situation, I think I can proceed with more confidence now. It all adds up, the mileage timing, the progression from intermittent to constant warnings, and the otherwise normal engine operation. Having proper car maintenance records showing similar issues around 150000 KM is particularly reassuring. I will schedule an appointment with my mechanic and specifically request a diagnostic of the oil sensor circuit and wiring harness inspection. The repair cost range you mentioned of 100-150 Euro seems reasonable compared to what I was worried it might be. Your experience with the worn wiring causing corrupted signals in the oil monitoring system while the sensor itself was fine matches my situation perfectly. I will make sure they perform the system scans as suggested to verify everything is resolved. This has been really helpful in narrowing down the problem and knowing what to expect. I feel much better knowing its likely just an electrical issue rather than a serious engine oil pressure problem.