Code No. P0403: EGR Valve DC Motor Malfunction

OPERATION

The electric current from the engine-ECU connector terminal EGR+ and EGR- to the EGR valve (DC motor) connector terminal 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 JUDGEMENT

Check Condition

Ignition switch is in "ON" position

Judgement 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).

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. Check EGR valve itself.

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

Q. Is the check result normal?

	Go to Step 2.

	Replace the EGR valve assembly.

STEP 2. Check of open circuit, short to earth, and damage in EGR+ line between EGR valve assembly connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 3.

	Repair the connector(s) or wiring harness.

STEP 3. Check of open circuit, short to earth, and damage in EGR- line between EGR valve assembly connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 4.

	Repair the connector(s) or wiring harness.

STEP 4. 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 set.

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).