Code No. P0489: Exhaust Gas Recirculation Valve (stepper motor) Circuit Malfunction (earth short)




OPERATION




FUNCTION




TROUBLE JUDGEMENT


Check Conditions
Judgement Criterion

FAIL-SAFE AND BACKUP FUNCTION




PROBABLE CAUSES




DIAGNOSIS PROCEDURE


STEP 1. Check exhaust gas recirculation valve (stepper motor) itself.



  • Exhaust gas recirculation valve connector check.
  • Exhaust gas recirculation valve (stepper motor) check (Refer to GROUP 17 - Emission Control <PHEV> - Exhaust Gas Recirculation (EGR) System - Exhaust Gas Recirculation Valve (Stepper Motor) Check ).

Q. Is the check result normal?

Go to Step 2.
Repair or replace the connector, or replace the exhaust gas recirculation valve.

STEP 2. Perform voltage measurement at exhaust gas recirculation valve connector.



  • Disconnect connector and measure at harness side.
  • Power supply mode of electric motor switch: ACC
  • Voltage between terminal power supply line and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 3.

    Repair or replace the connector, or check and repair harness between exhaust gas recirculation valve connector terminal and engine control relay connector terminal.

    • Check power supply line for open/short circuit.

STEP 3. Perform voltage measurement at engine-ECU connector.



  • Disconnect engine-ECU connector, and connect special tool power plant ECU check harness (MB992110) to measure at connector for inspection.
  • Power supply mode of electric motor switch: OFF → ACC
  • Voltage between terminal EGRA, EGRB, EGRC, EGRD and body earth.
OK: To initialise, energise exhaust gas recirculation valve for three seconds and de-energise it.

Q. Is the check result normal?

Go to Step 6.
Go to Step 4.

STEP 4. Check harness between exhaust gas recirculation valve connector terminal and engine-ECU connector terminal EGRA, EGRB, EGRC, EGRD.



  • Check output line for open/short circuit.

Q. Are the check results normal?

Go to Step 5.
Repair or replace the connector, or repair the damaged harness wire.

STEP 5. M.U.T.-III diagnosis code



  • Reconfirmation of diagnosis code.

Q. Is diagnosis code stored?

Replace the engine-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 6. Check harness between exhaust gas recirculation valve connector terminal and engine-ECU connector terminal EGRA, EGRB, EGRC, EGRD.



  • Check output line for damage.

Q. Are the check results normal?

Go to Step 7.
Repair or replace the connector, or repair the damaged harness wire.

STEP 7. Check harness between exhaust gas recirculation valve connector terminal and engine control relay connector terminal.



  • Check power supply line for damage.

Q. Is the check result normal?

Go to Step 5.
Repair or replace the connector, or repair the damaged harness wire.