I had the oil pump in my 2020 M340i replaced recently. There were two symptoms:
- Unable to read the oil pressure under any circumstance.
- Audible engine whine after engine is fully warmed up.
Replacing the pump fixed both problems. I can drive the car as long and as hard as I want, and immediately park and measure the oil successfully. The original oil pump for my car was replaced with an updated version that has a different part number. Rumor has it that the original pump had some internal plastic parts that are susceptible to failure and that the new pump uses metal.