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 JUDGEMENT

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.

Judgement Criterion

The EGR flow rate is lower than the specified value.

FAIL-SAFE AND BACKUP FUNCTION

The AS&G control is prohibited.

PROBABLE CAUSES

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

DIAGNOSIS PROCEDURE

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

Q. Is diagnosis code No. P0403 or No. P2413 set?

	Inspection chart for diagnosis codes (Refer to ).

	Go to Step 2.

STEP 2. Check harness between engine-ECU connector terminal EGR+ and exhaust gas recirculation valve 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 exhaust gas recirculation valve 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 exhaust gas recirculation valve 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 exhaust gas recirculation valve 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 exhaust gas recirculation valve 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 exhaust gas recirculation valve itself.

Exhaust gas recirculation valve connector check.
Check exhaust gas recirculation valve itself [Refer to GROUP 17 - Emission Control - Exhaust Gas Recirculation (EGR) System - exhaust gas recirculation valve (DC motor) Check ].

Q. Is the check result normal?

	Go to Step 8.

	Repair or replace the connector, or replace the exhaust gas recirculation valve.

STEP 8. Check EGR passage for deposits.

Check the exhaust gas recirculation valve, the EGR valve pipe and the inside of the EGR cooler for deposits. (Refer to GROUP 17 - Emission Control - EGR Valve and EGR Cooler ).

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.

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, erasing the diagnosis code through M.U.T.-III, ignition switch is "ON" position and confirm whether the diagnosis code is set.

Q. Is diagnosis code No. P0401 set again?

	Replace the engine-ECU.

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