Technical Description of OBD-II Trouble Code
Circuit for Engine Oil Pressure Sensor/Switch
This powertrain code (DTC) is a generic OBD-II code that applies to all vehicle makes and models (1996-newer). However, the specific repair steps may vary depending on the model. While the P0520 engine code is more commonly seen in Chevrolet, Dodge, GMC, Mercedes Benz, Pontiac, and Cadillac vehicles, it can occur in any make or model.
What does this mean?
The Powertrain Control Module (PCM), which is the main computer in the vehicle, controls various sensors, controls, and electronics. One of these sensors is the oil pressure sensor or sender, which detects the mechanical oil pressure in the engine and sends a voltage reading/value to the PCM. In some vehicles, this oil pressure value is displayed on a gauge in the instrument cluster, while in others, a warning light indicates any issues with the oil pressure.
The P0520 diagnostic engine code is triggered when the PCM detects a value from the engine oil pressure sender that is outside the normal range. In most cases, this code is related to electrical issues. It is also associated with codes P0521, P0522, P0523, and P0524.
Symptoms
Common symptoms of a P0520 DTC may include:
Causes
Possible causes of a P0520 code include:
Diagnostic & Repair Steps
It is recommended to check for technical service bulletins (TSB) specific to your vehicle as a starting point. These bulletins may provide information about known issues and their fixes, saving time and money during diagnosis.
For example, there is a known bulletin for Dodge-Chrysler-Ram-Jeep models, numbered 18-034-14.
As a vehicle owner or DIYer, the first step is to check the oil level using the dipstick. Ensure that there is sufficient oil in the engine and that the oil filter or drain plug is not leaking. Low or no oil pressure can be caused by an unnoticed leak or insufficient oil after an oil change. There can be various reasons for a P0520 or related codes.
Next, visually inspect the wiring and connectors at the oil pressure sending unit. Look for any signs of damage such as broken or frayed wires, burnt spots, loose or exposed wiring, etc. Ensure that the electrical connections are tight and not contaminated with oil. Refer to a model-specific repair manual to locate the sender. Remember that codes only indicate where to begin diagnosis, not which parts to replace.
If no obvious issues are found, use a digital volt ohm meter (DVOM) to test the terminals at the oil pressure sensor and its associated wiring and harness. Compare the readings to the factory specifications. Specifically, check for shorts to ground and resistance that falls outside the specified range (which depends on the model/engine). Repair any issues as necessary.
In most cases, the fix will involve repairing a wiring issue or replacing the sensor. Replacement of the PCM should only be considered as a last resort after proper diagnosis.
