P0520 means Engine Oil Pressure Sensor/Switch Circuit Malfunction. There is an electrical fault in the oil pressure sensor or switch circuit, so the computer cannot trust the oil pressure reading. It is a generic OBD-II code, so the definition is the same on any make, but the most likely cause varies by engine; confirm with a scan tool and the service information for your vehicle before buying parts.
What P0520 means
Most engine sensors receive a 5-volt reference and return a signal between roughly 0 and 5 volts. Codes ending in circuit high or circuit low usually point to an electrical fault: an open circuit, a short or an unplugged connector. Range/performance codes mean a signal is present but disagrees with what the computer expects from the other sensors, which more often points to a dirty sensor, an air leak or a mechanical problem.
P0520 symptoms
- Oil pressure gauge reading zero, maximum or erratic
- Oil pressure warning light on
- Check engine light
Common causes of P0520
- Failed oil pressure sensor
- Damaged wiring or connector
- Oil leaking into the connector
How to diagnose P0520
- Confirm actual oil pressure with a mechanical gauge before anything else
- Inspect the sensor connector and wiring
- Check sensor power, ground and signal
Can you drive with P0520?
Only after a mechanical gauge confirms real oil pressure is normal. If pressure is actually low, stop driving.
P0520 tips
Always verify oil pressure with a mechanical gauge before blaming the sensor. On some GM V8s the oil pressure sensor and its small filter screen are a known failure item, causing a gauge that drops to zero or jumps around while actual pressure is normal.
Will P0520 clear itself?
If the fault stops, the computer turns off the check engine light by itself after several drive cycles without seeing it again, and the code stays in memory as history for a while. Clearing P0520 with a scan tool after a repair is fine, but if the cause is still there the code returns, sometimes within one drive. Disconnecting the battery also clears codes on most vehicles, but it erases learned fuel trims and idle settings as well.
Related codes
| Code | Meaning |
|---|---|
| P0521 | Engine Oil Pressure Sensor/Switch Range/Performance |
| P0522 | Engine Oil Pressure Sensor/Switch Low Voltage |
| P0523 | Engine Oil Pressure Sensor/Switch High Voltage |
Guides that help
When it is more than a sensor
Sensor codes are usually fixed with a sensor, a connector, wiring or a leak repair rather than major parts. If testing turns up internal engine trouble instead, see how to tell if an engine is blown and compare engines by code on our engines page.
Shipping is a flat $80.00 per order to US addresses, with 15-day free returns. Questions? Ask a parts specialist.