P0521

DTC P0521

DTC DESCRIPTOR
DTC P0521: Engine Oil Pressure (EOP) Sensor Performance




DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

CIRCUIT/SYSTEM DESCRIPTION
The engine oil pressure (EOP) sensor changes voltage based on the engine oil pressure. The EOP sensor is a 3-wire sensor comprising of the signal circuit, the low reference circuit and the 5-volt reference circuit. The engine control module (ECM) supplies 5 volts to the EOP sensor via the 5-volt reference circuit and provides ground via the EOP low reference circuit. The ECM monitors the signal circuit of the EOP sensor to determine if the engine oil pressure sensor voltage is within the normal operating range of approximately 1-4 volts. When the engine oil pressure is high, the EOP sensor voltage is high and the ECM senses a high signal voltage. When the engine oil pressure is low, the EOP sensor voltage is low and the ECM senses a low signal voltage. The ECM sends the EOP information to the instrument panel cluster (IPC) via GMLAN serial data message.

CONDITIONS FOR RUNNING THE DTC
The engine is running.

CONDITIONS FOR SETTING THE DTC
The ECM does not detect a change in the engine oil pressure of at least 34.5 kPa (5.0 psi) over a predetermined variance of the engine speed.

ACTION TAKEN WHEN THE DTC SETS
- The ECM records the operating conditions at the time the diagnostics test fails. The ECM displays this information in the Failure Records on the scan tool.
- The IPC illuminates the EOP indicator.

CONDITIONS FOR CLEARING THE DTC
- The DTC becomes history when the conditions for setting the DTC are no longer present.
- The history DTC clears after 40 malfunction free warm-up cycles.
- The ECM receives a clear code command from the scan tool.

CIRCUIT/SYSTEM VERIFICATION
With the scan tool installed, observe the Engine Oil Pressure Sensor parameter in the IPC ECM Data List. With the engine idling, the EOP sensor parameter should indicate a range of 0.7-2.5 volts.

CIRCUIT/SYSTEM TESTING
With the engine idling, install a scan tool and observe the Engine Oil Pressure Sensor parameter.
- If the Engine Oil Pressure Sensor parameter is not within the range of 0.7-2.5 volts, replace the EOP sensor.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

Engine Oil Pressure Sensor and/or Switch Replacement for the 3.9L engine