P0521
DTC P0521 (5.3L and 3.9L Engine)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptor
DTC P0521
- Engine Oil Pressure (EOP) Sensor Performance
Diagnostic Fault Information
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 EOP 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 a serial data message. The ECM can also predict oil pressure as a function of engine speed and engine temperature.
Conditions for Running the DTC
* The engine is running with engine speed between 700-3,500 RPM.
* Oil temperature is less than 150°C (302°F).
* Engine load stability is less than 250 kPa (36.2 psi).
* Engine predicted pressure is between 50 kPa (7.3 psi) and 400 kPa (58 psi).
* No crank sensor DTCs set.
* No coolant sensor DTCs set.
* No intake air temperature sensor DTCs set.
* No MAF DTCs set.
* No oil pressure sensor circuit DTCs set.
Conditions for Setting the DTC
The ECM detects that the difference between the predicted oil pressure and the actual oil pressure is either less than 47 kPa (6.8 psi) or greater than 50 kPa (7.3 psi).
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.
Reference Information
Schematic Reference
Instrument Cluster Schematics (Instrument Cluster Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information.
Circuit/System Verification
Engine ON, observe the Engine Oil Pressure Sensor parameter. The reading should be between 41-448 kPa (6-65 psi).
Circuit/System Testing
1. Engine ON, transmission in park, vary the engine speed by 500 RPM.
2. Verify the scan tool Engine Oil Pressure Sensor parameter changes by more than 34.5 kPa (5 psi).
• If less than 34.5 kPa (5 psi), refer to:
* Oil Pressure Diagnosis and Testing (Component Tests and General Diagnostics) for the 5.3L engine.
* Oil Pressure Diagnosis and Testing (Component Tests and General Diagnostics) for the 3.9L engine.
3. If the pressure tests normal, replace the EOP sensor.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Engine Oil Pressure Sensor and/or Switch Replacement (Service and Repair) for the 5.3L engine.
* Engine Oil Pressure Sensor and/or Switch Replacement (Service and Repair) for the 3.9L engine.