DTC P0521 3.8L Engine
Circuit Description
The engine oil pressure (EOP) sensor changes voltage based on engine oil pressure. The engine control module (ECM) monitors the signal circuit of the EOP sensor. When the oil pressure is high, the sensor voltage is high, and the ECM senses a high signal voltage. When the oil pressure is low, the 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.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0521 Engine Oil Pressure (EOP) Sensor Performance
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
The ECM does not detect a change in the EOP of at least 34.5 kPa (5.0 psi) over a predetermined variance of the engine speed.
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 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. |
| • | The ECM receives a clear code command from the scan tool. |
Diagnostic Aids
Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.
Refer to Testing for Intermittent Conditions and Poor Connections .
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Instrument Cluster Schematics or Engine Controls Schematics Connector End View Reference: Instrument Panel, Gages, and Console Connector End Views or to Powertrain Control Module Connector End Views or to Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Does the Engine Oil Pressure Sensor parameter display values that vary within the specified values when idling and accelerating the engine? | 0.7-2.5 V | Go to Diagnostic Aids | Go to Step 3 |
3 | Replace the engine oil pressure (EOP) sensor. Refer to Engine Oil Pressure Sensor and/or Switch Replacement for the 3.8 L engine. Did you complete the replacement? | -- | Go to Step 4 | -- |
4 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
DTC P0521 5.3L Engine
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
DTC Descriptor
DTC P0521: Engine Oil Pressure (EOP) Sensor PerformanceDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Engine Oil Pressure 5-Volts 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 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. |
| • | The ECM receives a clear code command from the scan tool. |
Reference Information
Schematic Reference
Connector End View Reference
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
- Engine ON, transmission in park, vary the engine speed by 500 RPM.
- Verify the scan tool Engine Oil Pressure Sensor parameter changes by more than 34.5 kPa (5 psi).
- If the pressure tests normal, replace the EOP sensor.
| ⇒ | If less than 34.5 kPa (5 psi), refer to Oil Pressure Diagnosis and Testing . |
Repair Instructions
