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DTC P0521, P0522, or P0523

DTC P0521, P0522, or P0523

Diagnostic Instructions


Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.


DTC Descriptors

DTC P0521

Engine Oil Pressure Sensor Performance

DTC P0522

Engine Oil Pressure Sensor Circuit Low Voltage

DTC P0523

Engine Oil Pressure Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
5 V Reference P0522 P0523 P0523 P0521
Signal P0522 P0523 P0523 P0521
Low Reference - P0523 - P0521


Circuit/System Description

The engine oil pressure sensor changes voltage based on the engine oil pressure. The engine oil pressure sensor is a 3-wire sensor comprised of the signal circuit, the low reference circuit and the 5 V reference circuit. The engine control module (ECM) supplies 5 V to the engine oil pressure sensor via the 5 V reference circuit and provides ground via the engine oil pressure sensor low reference circuit. The ECM monitors the signal circuit of the engine oil pressure sensor to determine the engine oil pressure sensor voltage is within the normal operating range of approximately 1-4 V. When the engine oil pressure is high, the engine oil pressure sensor voltage is high and the sensor senses a high signal voltage. When the engine oil pressure is low, the engine oil pressure sensor voltage is low and the ECM senses a low signal voltage. The ECM sends the engine oil pressure sensor information via High Speed CAN-Bus to the body control module (BCM). The BCM then sends the engine oil pressure sensor information via Low Speed CAN-Bus to the instrument cluster.

Conditions for Running the DTC

The engine is running

Conditions for Setting the DTC


P0521

The engine oil pressure is out of its working range.

The ECM does not detect a change in the engine oil pressure.

The above condition is present over a predetermined variance of engine speed.



P0522

The ECM detects a short to ground in the engine oil pressure signal circuit.

The above condition is present for greater than 10 seconds.



P0523

The ECM detects a short to voltage or an open circuit in the engine oil pressure signal circuit.

The above condition is present for greater than 10 seconds.


Action Taken When the DTC Sets

The instrument cluster illuminates the service vehicle soon indicator.

Conditions for Clearing the DTC

The DTC becomes history when the conditions for setting the DTC are no longer present.

Reference Information

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation


Instrument Cluster Description and Operation

Indicator/Warning Message Description and Operation

Driver Information Center (DIC) Description and Operation


Electrical Information Reference


Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs


DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Engine running, observe the scan tool Engine Oil Pressure Sensor parameter. The reading should be between 0.3-4.8 V.

Circuit/System Testing


1. Ignition OFF, disconnect the harness connector at the B37B Engine Oil Pressure Sensor.

2. Ignition OFF, test for less than 10 Ω between the low reference circuit terminal 1 and ground.

3. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace K20 Engine Control Module.

4. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 2 and ground.

5. If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace K20 Engine Control Module.

6. If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.

7. Verify the scan tool Engine Oil Pressure Sensor parameter is greater than 4.8 V.

8. If less than the specified range, test pin 3 of the signal circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module.

9. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the low reference circuit terminal 1. Verify the scan tool Engine Oil Pressure Sensor parameter is less than 0.3 V.

10. If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace K20 Engine Control Module.

11. If all circuits test normal, replace the B37B Engine Oil Pressure Sensor.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


Engine Oil Pressure Sensor and/or Switch Replacement (LAU) Engine Oil Pressure Sensor and/or Switch Replacement (LF1 or LFW)

Control Module References for ECM replacement, setup and programming.