DTC P0521 3.5L Engine

Diagnostic Instructions

DTC Descriptor

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

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Engine Oil Pressure 5-Volt Reference Circuit	P0522	P0522	--	P0521
Engine Oil Pressure Sensor Signal Circuit	P0522	P0522	P0523	P0521
Low Reference	--	P0523	--	P0521

Circuit/System Description

The engine oil pressure (EOP) sensor changes voltage based on 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 the serial data circuit.

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

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

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.

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.

⇒	If not within the range of 0.7 V - 2.8 V, replace the EOP sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Engine Oil Pressure Sensor and/or Switch Replacement

DTC P0521 3.9L and 5.3L Engine

Diagnostic Instructions

DTC Descriptor

DTC P0521: Engine Oil Pressure (EOP) Sensor Performance

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Engine Oil Pressure 5-Volts Reference	P0522	P0522	--	P0521
Engine Oil Pressure Sensor Signal	P0522	P0522	P0523	P0521
Low Reference	--	P0523	--	P0521

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

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

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Displays and Gages Connector End Views

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List 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 .

3. If the pressure tests normal, replace the EOP sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.