P0488

DTC P0488

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Strategy Based Diagnosis Strategy Based Diagnosis
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions

DTC Descriptors
DTC P0488
- Exhaust Gas Recirculation (EGR) Closed Valve Pintle Error

Diagnostic Fault Information






Typical Scan Tool Data






Circuit Description

Voltage is provided to the exhaust gas recirculation (EGR) valve by the ignition 1 voltage circuit through a fuse. Ground is provided to the EGR valve on the control circuit by a low side driver within the engine control module (ECM). The ECM monitors the voltage on the control circuit of the EGR valve to determine if a failure is present.

The engine control module (ECM) monitors the position of the exhaust gas recirculation (EGR) valve through the EGR valve position sensor. The EGR valve position sensor sends a feedback voltage on the signal circuit to the ECM. The EGR position sensor voltage varies depending on the position of the EGR valve.

The EGR valve utilizes the following circuits:

* An ignition 1 voltage circuit
* A control circuit
* A 5-volt reference circuit
* A signal circuit
* A low reference circuit

Conditions for Running the DTC

* DTCs P0112, P0113, P0405, P0406, and P0502 are not set.
* The engine is running
* The intake air temperature (IAT) is greater than 3°C (37°F).
* The ignition voltage is between 11.7-16 volts.
* The desired EGR position is equal to 0.
* The DTC run continuously when the above conditions are met.

Conditions for Setting the DTC

The ECM detects the difference between the actual EGR position and the learned EGR position is greater than 10 percent.

Action Taken When the DTC Sets

DTC P0488 is a Type B DTC.

Conditions for Clearing the DTC

DTC P0488 is a Type B DTC.

Diagnostic Aids

* If a shared 5-volt reference circuit is shorted to ground or shorted to a voltage, other 5-volt reference circuits may be affected.
* The scan tool 5-volt reference parameter should display between 4.8-5.2 volts.

Reference Information

Schematic Reference

Engine Controls Schematics (w/Throttle Actuator Controls) Electrical DiagramsEngine Controls Schematics (w/o Throttle Actuator Control) Electrical Diagrams

Connector End View Reference
* Engine Control Module Connector End Views (w/ Throttle Actuator Control) Engine Control Module Connector End Views (w/ Throttle Actuator Control)Engine Control Module Connector End Views (w/o Throttle Actuator Control) Engine Control Module Connector End Views (w/o Throttle Actuator Control)
* Engine Controls Connector End Views (w/ Throttle Actuator Control) Engine Controls Connector End Views (w/ Throttle Actuator Control)Engine Controls Connector End Views (w/o Throttle Actuator Control) Engine Controls Connector End Views (w/o Throttle Actuator Control)

Description and Operation

Exhaust Gas Recirculation (EGR) System Description Description and Operation

Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference
* Scan Tool Data List (w/ Throttle Actuator Control) Scan Tool Data List (w/ Throttle Actuator Control)Scan Tool Data List (w/o Throttle Actuator Control) Scan Tool Data List (w/o Throttle Actuator Control)
* Scan Tool Data Definitions (w/ Throttle Actuator Control) Scan Tool Data Definitions (w/ Throttle Actuator Control)Scan Tool Data Definitions (w/o Throttle Actuator Control) Scan Tool Data Definitions (w/o Throttle Actuator Control)
* Scan Tool Output Controls (w/ Throttle Actuator Control) Scan Tool Output Controls (w/ Throttle Actuator Control)Scan Tool Output Controls (w/o Throttle Actuator Control) Scan Tool Output Controls (w/o Throttle Actuator Control)

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. Verify DTC P0651 is not set.

• If DTC P0651 is set, refer to DTC P0641 or P0651 P0641.

2. Observe the EGR Position Variance parameter while commanding the EGR valve to 100 percent. The reading should be less than 15 percent.
3. Engine running, observe the EGR position sensor percentage parameter. The reading should be less than 4 percent.
4. If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector of the EGR valve.
2. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit and ground.

• If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.

3. Ignition OFF, verify a test lamp does not illuminate between the control circuit and B+.

• If test lamp illuminates, test the control circuit for a short to ground. If the circuit/connections test normal, replace the ECM.

4. Ignition ON, With a scan tool, command the EGR valve to 100 percent. The test lamp should illuminate.

• If test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM.

5. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit and ground.

• If greater than 1 ohm, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.

Important: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components.


6. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit and ground.

• If less than 4.8 volts, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM.

• If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.

7. Ignition ON, verify that the EGR position sensor parameter is less than 3 percent.

• If greater than 3 percent, test the signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.

8. Ignition ON, install a 3-amp fused jumper wire between the signal circuit and the 5-volt reference circuit. Verify that the EGR position sensor parameter is greater than 95 percent.

• If less than 95 percent, test the signal circuit for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.

9. If all circuits/connections test normal, test or replace the EGR valve.

Component Testing

1. Ignition OFF, disconnect the harness connector of the exhaust gas recirculation (EGR) valve.
2. Measure for 6-10 ohms of resistance between the ignition 1 voltage and control circuit terminal of the EGR valve.

• If the resistance is out of the specified range, replace the EGR valve.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Exhaust Gas Recirculation Valve Replacement Service and Repair
* Control Module References Control Module References for engine control module replacement, setup, and programming