GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Corvette 🢒 Body and Accessories 🢒 Instrument Panel, Gauges, and Console 🢒 DTC P0523

Circuit Description

The Engine Oil Pressure (EOP) sensor measures changes in engine oil pressure.

The EOP sensor changes resistance based on changes in engine oil pressure. When the PCM senses a signal voltage lower than the normal operating range of the sensor, this DTC sets.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

The engine oil pressure sensor voltage is greater than 4.5 volts.

Action Taken When the DTC Sets
    • The PCM stores the DTC information into memory when the diagnostic runs and fails.
    • The Malfunction Indicator Lamp (MIL) will not illuminate.
    • The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
    • The driver information center displays a message.
    • The engine oil pressure gage displays 0 psi.

Conditions for Clearing the MIL or DTC
    • A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
    • A last test failed, ore current DTC, will clear when the diagnostic runs and does not fail.
    • Use a scan tool in order to clear the MIL or DTC.

Diagnostic Aids

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the module. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM.

    • An open ground circuit may not set this DTC. Inspect the ground circuit for an open if the EOP gage displays the maximum pressure.
    • The PCM 5.0 volt reference circuits are internally connected within the PCM. If all the engine oil pressure sensor circuits are OK, inspect related 5.0 volt reference circuits. Refer to DTC P1635 in Engine Controls.
    • For an intermittent, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step determines if the malfunction is present.

  2. Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.) that you observed. This isolates when the DTC failed.

    3.

  3. This step tests if the signal circuit is shorted to a voltage.

    4.

  4. This step verifies if a ground circuit is available at the EOP sensor.

Step

Action

Values

Yes

No

Schematic Reference: Instrument Cluster Schematics

1

Did you perform the IPC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2

Important: Before proceeding with the engine oil pressure sensor diagnostic, perform the engine oil pressure test. Refer to Oil Pressure Diagnosis and Testing in Engine Mechanical.

  1. Install the scan tool.
  2. Start the engine.
  3. Monitor the DTC Information using the scan tool.

Did DTC P1635 fail this ignition cycle?

--

Go to DTC P1635 in Engine Controls

Go to Step 3

3

  1. Turn ON the ignition leaving the engine OFF.
  2. Monitor the PCM Engine Data 3 Engine Oil Pressure voltage using the scan tool.

Is the Engine Oil Pressure sensor voltage above the specified value?

4.5 V

Go to Step 5

Go to Step 4

4

  1. Turn ON the ignition leaving the engine OFF.
  2. Review the Freeze Frame and/or Failure Records data for this DTC and note parameters.
  3. Turn OFF the ignition for 15 seconds.
  4. Start the engine and operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame/Failure Records as possible. Special operating conditions that need to be met before the PCM will run this diagnostic, where applicable, are listed in Conditions for Running the DTC.
  5. Select the Diagnostic Trouble Code (DTC) option, the Specific DTC option, and enter the DTC number using the scan tool.

Does the scan tool indicate that this diagnostic failed this ignition?

--

Go to Step 5

Go to Diagnostic Aids

5

  1. Disconnect the engine oil pressure sensor electrical connector. Refer to Engine Oil Pressure Sensor or Switch Replacement .
  2. Observe the Engine Oil Pressure sensor voltage displayed on the scan tool.

Is the Engine Oil Pressure sensor voltage below the specified value?

1 V

Go to Step 6

Go to Step 7

6

Probe the sensor ground circuit with the test lamp to B+. Refer to Circuit Testing in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 8

Go to Step 9

7

Test the engine oil pressure signal circuit for a short to voltage or a short to the 5 volt reference circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 11

8

Measure the voltage at the 5 volt reference circuit to ground using the DMM. Refer to Circuit Testing in Wiring Systems.

Is the voltage greater than the specified value?

5 V

Go to Step 13

Go to Step 12

9
  1. Disconnect the PCM connector C1 located on the same side as the manufacturer's logo. Refer to Powertrain Control Module Replacement in Engine Controls-5.7 L.
  2. Inspect for a poor sensor ground terminal connection at the PCM connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 10

10

Test for continuity of the engine oil pressure sensor ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

2 ohms

Go to Step 14

Go to Step 11

11

Important: Program the replacement PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls.

Did you complete the replacement?

--

Go to Step 14

--

12

Important: Before replacing the sensor inspect for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Replace the EOP sensor. Refer to Engine Oil Pressure Sensor or Switch Replacement .

Did you complete the replacement?

--

Go to Step 14

--

13

Repair the 5.0 volt reference circuit for a short to voltage. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 14

--

14
  1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC option using the scan tool.
  2. Start the engine and idle at the normal operating temperature.
  3. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
  4. Operate vehicle within the Conditions for Running this DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

--

Go to Step 15

Go to Step 2

15

Select the Capture Info option and the Review Info option using the scan tool.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to the applicable DTC table

System OK