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. Initial Inspection and Diagnostic Overview






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 idling at less than 640 RPM and EOP sensor performance check is high.
* The engine is running at greater than 1,520 RPM and EOP sensor performance check is low.

Conditions for Setting the DTC

* The engine oil pressure is greater than 880 kPa (127.6 psi).
* The engine oil pressure is less than 8 kPa (1.16 psi).
* 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 and the engine idling, the Engine Oil Pressure Sensor parameter should indicate a range of 0.7-2.8 volts or 8 kPa (1.16 psi) - 880 kPa (127.6 psi).

Circuit/System Testing

1. Ignition ON and the engine idling, verify the scan tool Engine Oil Pressure Sensor parameter is within 0.7 V - 2.8 V or 8 kPa (1.16 psi) - 880 kPa (127.6 psi).

• If not within the range of 0.7 V - 2.8 V or 8 kPa (1.16 psi) - 880 kPa (127.6 psi), 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 4.6L engine
* Engine Oil Pressure Sensor and/or Switch Replacement for the 4.4L engine
* Engine Oil Pressure Sensor and/or Switch Replacement for the 3.6L engine