What does it mean?
P1520 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Engine Oil Quality Sensor Level Measurement Error .
Symptoms
- Check engine light or an oil level warning message in the instrument cluster
- Oil level display missing, erratic or jumping between values
- Service interval or oil life calculation clearly wrong
- Warning appears mainly when the car is parked on an incline
- No change in engine performance or noise
- Warning may clear itself after a restart and return later
Likely causes
- Engine oil level genuinely too low, or overfilled above the sensor range
- Sludge and carbon deposits coating the sensor element
- Oil of the wrong specification or viscosity, or heavily diluted with fuel
- Damaged connector at the sensor, which sits low on the engine and is exposed to leaks and road salt
- Chafed or corroded wiring between the sensor and the module
- Internal sensor failure or a lost calibration
- Measurement attempted while the vehicle stands on a slope, repeated often enough to set the code
How to fix it
- Check the actual oil level with the specified procedure on level ground with the engine cold
- Check whether the oil grade and condition match the manufacturer specification, and change it if it is contaminated or fuel diluted
- Inspect the sensor connector for oil contamination, corrosion and loose terminals
- Read the sensor values in live data and see whether they respond when oil is added
- Measure the supply, ground and signal circuits between the sensor and the module
- Replace the oil level and quality sensor if the circuit is good but the reading stays implausible
- Reset the oil quality and service data after the repair and re-run the level measurement