The BMW Diagnostic Trouble Code (DTC) P0520 corresponds to an "Engine Oil Pressure Sensor/Switch Circuit" malfunction. Here's what it typically means:
**P0520 - Engine Oil Pressure Sensor/Switch Circuit**
This DTC indicates that the engine control module (ECM) has detected a malfunction or issue with the engine oil pressure sensor or oil pressure switch circuit. The oil pressure sensor or switch is responsible for monitoring the engine's oil pressure and providing data to the ECM to ensure proper lubrication.
Common causes of a P0520 code in a BMW include:
1. **Faulty Engine Oil Pressure Sensor or Switch:** The oil pressure sensor or switch itself may be malfunctioning or providing incorrect readings.
2. **Wiring or Connector Issues:** Damaged or corroded wiring, connectors, or terminals related to the oil pressure sensor or switch can result in a circuit malfunction.
3. **Low Engine Oil Level:** Insufficient engine oil can lead to low oil pressure, triggering this code. It's important to check and maintain the engine oil level.
4. **Oil Pressure Relief Valve Issues:** Problems with the oil pressure relief valve can affect oil pressure and trigger this code.
To diagnose and address a P0520 code, a qualified technician typically performs the following steps:
1. **Visual Inspection:** Inspect the wiring, connectors, and terminals related to the oil pressure sensor or switch for damage, corrosion, or loose connections.
2. **Check Engine Oil Level:** Ensure that the engine oil level is at the correct level. Low oil level can lead to low oil pressure.
3. **Test the Oil Pressure Sensor or Switch:** Test the oil pressure sensor or switch for proper function, including resistance or voltage readings, depending on the sensor type.
4. **Inspect the Oil Pressure Relief Valve:** Check the oil pressure relief valve to ensure it is functioning correctly and not sticking.
5. **Data Monitoring:** Use a diagnostic scan tool to monitor live data, including oil pressure readings, to help identify any discrepancies or abnormalities.