Code P0520 on the 2024 GMC Sierra indicates a malfunction in the engine oil pressure sensor or switch circuit. While the ECM may use this data for oil life monitoring, P0520 specifically indicates an electrical circuit fault in the oil pressure sensing system.
Oil Pressure Sensing
The oil pressure sensor provides critical data about engine lubrication system health. The ECM monitors this signal for safety warnings and may use it alongside other data for oil life calculation. The sensor converts hydraulic pressure to an electrical signal the ECM can interpret.
Circuit Fault vs. Low Pressure
P0520 indicates an electrical problem - the signal is out of expected range or showing circuit fault characteristics. This could be high resistance, shorted wiring, or sensor failure. It doesn't necessarily mean oil pressure is actually low, but that the circuit reading is abnormal.
Diagnostic Priority
Never assume P0520 is just a sensor issue without verification. First confirm actual oil pressure with a mechanical gauge. If pressure is adequate, the fault is electrical. If pressure is actually low, that's a serious mechanical issue requiring immediate attention.
Common Causes
Faulty oil pressure sensor (common failure item), corroded connector, damaged wiring near the hot engine, or low oil level affecting sensor readings are typical causes.