Code No. P0403: EGR Valve DC Motor Malfunction


OPERATION



  • The electric current from the engine-ECU (terminal No. 115 and No. 130) to the EGR valve (DC motor) (terminal No. 4 and No. 6) is controlled.

FUNCTION



  • The engine-ECU performs duty control over the EGR valve (DC motor).
  • The engine-ECU performs feedback control over the EGR valve based on the signals from the EGR position sensor.

TROUBLE JUDGMENT


Check Condition
  • Ignition switch is in "ON" position
Judgment Criterion
  • An over current cut-off signal from the EGR valve drive control integrated circuit (IC) is detected.

FAIL-SAFE AND BACKUP FUNCTION



  • The DPF regeneration is prohibited.
  • The throttle valve is opened (Electrical discontinuity).
  • The EGR control is stopped (fully closed).
  • The AS&G control is prohibited.

PROBABLE CAUSES



  • Failed EGR valve
  • Open/short circuit or harness damage in EGR valve circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-16 EGR valve assembly connector.

Q. Is the check result normal?
Go to Step 2 .
Repair or replace the connector.

STEP 2. Check EGR valve itself.

  • Check EGR valve itself [Refer to GROUP 17 - Emission Control <DIESEL> - Exhaust Gas Recirculation (EGR) System - Exhaust Gas Recirculation Valve (DC motor) Check ].

Q. Is the check result normal?
Go to Step 3 .
Replace the EGR valve assembly.

STEP 3. Connector check: B-10 engine-ECU connector.

Q. Is the check result normal?
Go to Step 4 .
Repair or replace the connector.

STEP 4. Check harness between B-10 (terminal No. 115) engine-ECU connector and B-16 (terminal No. 6) EGR valve assembly connector.
note Before checking harness, check intermediate connector A-17, and repair if necessary.

  • Check output line for open/short circuit and damage.

Q. Is the check result normal?
Go to Step 5 .
Repair the damaged harness wire.

STEP 5. Check harness between B-10 (terminal No. 130) engine-ECU connector and B-16 (terminal No. 4) EGR valve connector.
note Before checking harness, check intermediate connector A-17, and repair if necessary.

  • Check output line for open/short circuit and damage.

Q. Is the check result normal?
Go to Step 6 .
Repair the damaged harness wire.

STEP 6. M.U.T.-III diagnosis code

  • After clearing the diagnosis code through M.U.T.-III, start the engine and confirm whether the diagnosis code is output.

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