BMW Z3 Oil Level Sensor Problems, Fixes and Solutions

Hey there! I had a similar issue with my 2004 BMW Z4 last year. The symptoms were pretty much identical, those annoying oil warnings and sensor readings going crazy. My mechanic found that the wiring connector to the oil level sensor was corroded and had a loose connection. The total fix was around 95 Euro, mainly labor costs for diagnosing and replacing the faulty connection and cleaning up the plug area. Since then, everything's been working perfectly on my Z4 (and my previous 3 series never had this issue). Could you share more details about what specific error codes you're getting? This would help confirm if it's the same problem I encountered. Also, have you noticed any oil spots under the car or any unusual engine sounds?

Thanks for sharing your experience! My Z3 just hit 126786 KM and had its last service two months ago. Haven't noticed any oil spots under the car, and the engine sounds normal. Getting error codes P0520 and P0521 mainly. The repair cost you mentioned sounds reasonable, definitely better than replacing the entire sensor unit! Did you have any issues with the wiring after the fix? I've heard these connectors can be tricky to properly seal against moisture.

Hey again! Thanks for the follow-up about your Z3. Those error codes definitely match what I experienced with my Z4, they're classic indicators of oil pressure sensor circuit issues. After my repair last year, I haven't had any problems with the wiring at all. My mechanic actually used some dielectric grease on the connector when reinstalling it, which helps prevent future corrosion and moisture issues. Smart move on his part, I'd say! One thing I should mention, while my fix was straightforward, I've heard from other Z3/Z4 owners that sometimes the connector itself isn't the only culprit. The wiring harness can develop small cracks in the insulation over time, especially near bend points. But given that your car just had service and you're not seeing any oil spots, I'm betting you're dealing with the same connector issue I had. Quick tip: if you decide to get it fixed, make sure they check the entire length of the sensor wiring while they're in there. It's a bit more thorough, but it could save you from having to deal with this again down the road. Mine's been running like a charm for over 15 months now since the fix.

Thanks so much for the detailed response and that great tip about the dielectric grease! I've scheduled an appointment with my mechanic for next week and I'll definitely mention checking the entire wiring harness like you suggested. It's really reassuring to hear your repair has held up well for over 15 months. Makes total sense about the bend points too, never thought about that being a potential issue. Really appreciate you sharing your experience. Will update the thread once I get it fixed in case anyone else runs into similar problems with their Z3. Thanks again for all the helpful info!