For 1990-2009 cars

### 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 | --
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. The ECM tests the state of the EOP circuit with the ignition switch turned ON, and the engine turned OFF. When the oil pressure is low, the ECM sends a serial data message to the body control module (BCM) requesting the EOP indicator turned ON. The instrument panel cluster (IPC) illuminates the EOP indicator when the IPC receives a serial data message from the BCM requesting the EOP indicator turned ON.

### 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

#### 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 Engine Oil Pressure Switch parameter is OK.

⇒ | If not the specified value, refer to:

• | Oil Pressure Diagnosis and Testing for the 2.0L engine.

• | Oil Pressure Diagnosis and Testing for the 2.4L engine.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the engine oil pressure (EOP) switch.
2. Ignition ON, verify the scan tool Engine Oil Pressure Switch parameter is OK.

⇒ | If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the ECM.

3. Ignition ON, install a 3-A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool Engine Oil Pressure Switch parameter is Low.

⇒ | 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/PCM.

4. 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 Replacement for the 2.2 or 2.4L engine

• | Engine Oil Pressure Sensor and/or Switch Replacement for the 2.0L engine

• | Control Module References for the ECM replacement, setup, and programming