GM Service Manual Online
For 1990-2009 cars only

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 Descriptor

DTC P0520 : Engine Oil Pressure (EOP) Sensor Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Engine Oil Pressure Switch Signal

1

P0520

P0520

--

Engine Oil Pressure Switch Ground

--

P0520

--

--

1. Engine Oil Pressure Indicator Malfunction

Circuit/System Description

The engine oil pressure (EOP) switch is a normally closed switch that opens with the proper oil pressure. With the ignition switch turned ON and the engine not running, the engine control module (ECM) should detect a low signal voltage input. With the engine running, the pressure switch opens, and the ECM should detect a high signal voltage input. When the oil pressure is low, the ECM sends a serial data message to the IPC requesting the EOP indicator turned ON.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

    • The ECM detects that the EOP switch signal circuit is pulled low.
    • The above condition is present for greater than 10 seconds.

Action Taken When the DTC Sets

    • The ECM records the operating conditions at the time the diagnostic test fails. The ECM displays this information in the Failure Records on the scan tool.
    • The instrument panel cluster (IPC) illuminates the engine oil pressure 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

Connector End View Reference

Component Connector End Views

Description and Operation

Instrument Cluster Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, engine running, verify the scan tool Oil Pressure parameter is Normal.

If not the specified value, refer to Oil Pressure Diagnosis and Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the engine oil pressure (EOP) switch.
  2. Ignition ON, verify the scan tool Oil Pressure parameter is Normal.
  3. If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the ECM.
  4. Ignition ON, install a 3-Amp fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool Oil Pressure parameter is Low Pressure.
  5. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  6. If all circuits test normal, replace the engine oil pressure switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Engine Oil Pressure Sensor and/or Switch Replacement
    •  Control Module References for the ECM replacement, setup, and programming