Code No. P0401: EGR Flow Insufficient

OPERATION

Refer to Code No. P0102: Air Flow Sensor Circuit Low Input .
Refer to Code No. P0403: EGR Valve DC Motor Malfunction .
Refer to Code No. P0489: EGR Valve Position Sensor Circuit Low Input .

FUNCTION

The engine ECU monitors the EGR flow rate.

TROUBLE JUDGMENT

Check Condition

The amount of fuel consumption, the engine speed, the target lambda, the gear position, the vehicle speed, the intake air temperature and the atmospheric pressure are within the threshold values.

Judgment Criterion

The EGR flow rate is lower than the specified value.

FAIL-SAFE AND BACKUP FUNCTION

The small injection quantity learning is prohibited.
The AS&G control is prohibited.

PROBABLE CAUSES

Failed EGR passage (leakage and clogged EGR passage)
Failed connector or harness damage of EGR valve system
Failed EGR valve operation
Failed connector or harness damage of AFS system
Failed AFS (abnormal output characteristics)
Failed engine-ECU

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III diagnosis code

Q. Is the diagnosis code P0403 or P2413 stored?

	Inspection chart for diagnosis codes (Refer to ).

	Go to Step 2.

STEP 2. Check harness between engine-ECU connector terminal EGR+ and EGR valve assembly connector terminal.

Check output line for damage.

Q. Is the check result normal?

	Go to Step 3.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 3. Check harness between engine-ECU connector terminal EGR- and EGR valve assembly connector terminal.

Check output line for damage.

Q. Is the check result normal?

	Go to Step 4.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 4. Check harness between engine-ECU connector terminal EGRE and EGR valve assembly connector terminal.

Check earthing line for damage.

Q. Is the check result normal?

	Go to Step 5.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 5. Check harness between engine-ECU connector terminal EGR5 and EGR valve assembly connector terminal.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 6.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 6. Check harness between engine-ECU connector terminal EGRP and EGR valve assembly connector terminal.

Check output line for damage.

Q. Is the check result normal?

	Go to Step 7.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 7. Check EGR valve itself.

EGR valve connector check.
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 8.

	Repair or replace the connector, or replace the EGR valve assembly.

STEP 8. Check EGR passage for deposits.

Check the EGR valve, the EGR valve pipe and the inside of the EGR cooler for deposits. (Refer to GROUP 17 - Emission Control <DIESEL> - Exhaust Gas Recirculation (EGR) Valve - Removal And Installation and refer to GROUP 17 - Emission Control <DIESEL> - EGR Cooler - Removal And Installation <M/T>, <A/T>).

Q. Is the check result normal?

	Go to Step 9.

	Cleaning or replace the EGR valve, EGR valve pipe and EGR cooler.

STEP 9. Check harness between air flow sensor connector terminal and engine-ECU connector terminal AFSE&ECBE.

Check earthing line for damage.

Q. Is the check result normal?

	Go to Step 10.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 10. Check harness between air flow sensor connector terminal and engine-ECU connector terminal AFS.

Check output line for damage.

Q. Is the check result normal?

	Go to Step 11.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 11. Replace the air flow sensor.

After replacing the air flow sensor, re-check the trouble symptoms.

Q. Is the check result normal?

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

	Replace the engine-ECU.