Diagnostic Instructions
DTC Descriptor
DTC P0409: Exhaust Gas Recirculation (EGR) Position Sensor Performance
Circuit/System Description
The exhaust gas recirculation (EGR) valve is driven by the EGR motor, and the EGR motor is controlled by the engine control module (ECM). The EGR position sensor generates a signal according to the position of the EGR motor. The EGR valve has the following
circuits:
| • | The EGR motor U position drive circuit |
| • | The EGR motor V position drive circuit |
| • | The EGR motor W position drive circuit |
| • | A 5-volt reference circuit |
| • | A low reference circuit |
| • | The EGR motor U position signal circuit |
| • | The EGR motor V position signal circuit |
| • | The EGR motor W position signal circuit |
The ECM supplies voltage to the EGR motor on the EGR motor drive circuits. The EGR valve is controlled by the time of voltage supply from the ECM to the EGR motor. When the time of voltage supply increases, the EGR valve position decreases. The ECM detects
the actual EGR valve operation with the mass air flow (MAF) ratio.
Conditions for Running the DTC
| • | DTCs P0652 and P0653 are not set. |
| • | The battery voltage is between 10-16 volts. |
| • | The ignition switch is ON for longer than 2 seconds. |
| • | The elapsed time from starter switch OFF if longer than 2 seconds. |
Conditions for Setting the DTC
The ECM detects EGR valve position signal is abnormal. The EGR position abnormal signal pattern is as follows:
| • | U, V, W position: ON, ON, ON |
| • | U, V, W position: OFF, OFF, OFF |
Action Taken When the DTC Sets
DTC P0409 is a Type A DTC.
Conditions for Clearing the DTC
DTC P0409 is a Type A DTC.
Diagnostic Aids
Inspect for any recent engine mechanical repairs. An incorrectly installed EGR valve will cause this DTC to set.
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
Verify the integrity of the EGR valve by inspecting for the following conditions:
| • | Loose or improper installation |
Circuit/System Testing
- Turn OFF the ignition and disconnect the EGR valve harness connector.
- Turn the ignition ON.
- Using a DMM, measure the voltage between the 5-volt reference circuit and a known good ground.
| ⇒ | If less than 4.8 volts, test the 5-volt reference circuit for an open. |
- Using a DMM, measure the voltage between the 5-volt reference circuit and the low reference circuit.
| ⇒ | If less than 4.8 volts, test the low reference circuit for an open. |
- Connect a test lamp between the position sensor signal circuits and a known good ground.
| ⇒ | If the test lamp illuminates, test the position sensor signal circuits for short to battery voltage. |
| ⇒ | If the test lamp does not illuminate, test the position sensor signal circuits for an open, short to ground, a
short to 5-volt reference circuit or a short to low reference circuit. |
- If the circuits are normal, replace the EGR valve.
- Connect all previously disconnected harness connectors.
- Clear the DTCs with a scan tool.
- Turn OFF the ignition for 30 seconds.
- Start the engine and observe the scan tool for the current DTCs.
| ⇒ | If the DTC fails this ignition, replace the ECM. |
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
