Code No. P0405: EGR Valve Position Sensor Circuit Low Input

OPERATION

A power voltage of 5 V is applied to the exhaust gas recirculation valve power terminal from the engine-ECU connector terminal EGR5 and earthed to the engine-ECU connector terminal EGRE from the exhaust gas recirculation valve connector terminal.
The sensor signal is inputted to the engine-ECU connector terminal EGRP from the exhaust gas recirculation valve output terminal.

FUNCTION

The exhaust gas recirculation valve detects the position of the exhaust gas recirculation valve and sends the signal to the engine-ECU.
Based on the signal, the engine-ECU performs the feedback control of the exhaust gas recirculation valve.

TROUBLE JUDGEMENT

Check Conditions

Battery positive voltage is 8 - 16 V
2 seconds later after the ignition switch has been in "ON" position or the engine has started up.

Judgement Criterion

The exhaust gas recirculation valve position sensor output voltage is 0.20 V or less.

FAIL-SAFE AND BACKUP FUNCTION

The EGR control is stopped (fully closed).

PROBABLE CAUSES

Failed exhaust gas recirculation valve position sensor
Open/short circuit or harness damage in exhaust gas recirculation valve position sensor circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

Refer to Data List Reference Table .

Item 16: EGR valve position sensor

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).

	Go to Step 2.

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

Use special tool test harness(MB991658) to connect connector and measure at pick-up harness.
Ignition switch: ON
Voltage between terminal engine-ECU EGR5 line and body earth.

OK: 4.9 - 5.1 V

Q. Is the check result normal?

	Go to Step 6.

	Go to Step 3.

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

Disconnect engine-ECU harness, and connect special tool power plant ECU check harness (MB992291) to measure at connector for inspection.
Ignition switch: ON
Voltage between terminal EGR5 and body earth.

OK: 4.9 - 5.1 V

Q. Is the check result normal?

	Repair or replace the connector, or check and repair harness between exhaust gas recirculation valve connector terminal and engine-ECU connector terminal EGR5. Check power supply line for open circuit and damage.

	Go to Step 4.

STEP 4. Check harness between exhaust gas recirculation valve connector terminal and engine-ECU connector terminal EGR5.

Check power supply line for short circuit.

Q. Is the check result normal?

	Go to Step 5.

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

STEP 5. M.U.T.-III data list

Refer to Data List Reference Table .

Item 16: EGR valve position sensor

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.

STEP 6. Perform resistance measurement at exhaust gas recirculation valve connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Resistance between terminal engine-ECU EGRE line and body earth.

OK: Continuity (2 Ω or less)

Q. Is the check result normal?

	Go to Step 8.

	Go to Step 7.

STEP 7. Check harness between exhaust gas recirculation valve connector terminal and engine-ECU connector terminal EGRE.

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 8. Perform voltage measurement at exhaust gas recirculation valve connector.

Use special tool test harness (MB991658) to connect connector and measure at pick-up harness.
Engine: Idling (after warming up)
Voltage between terminal engine-ECU EGRP line and body earth.

OK: 2.0 V or higher

Q. Is the check result normal?

	Go to Step 10.

	Go to Step 9.

STEP 9. Check harness between exhaust gas recirculation valve connector terminal and engine-ECU connector terminal EGRP.

Check output line for short circuit.

Q. Is the check result normal?

	Replace the exhaust gas recirculation valve.

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

STEP 10. Perform voltage measurement at engine-ECU connector.

Disconnect engine-ECU harness, and connect special tool power plant ECU check harness (MB992291) to measure at connector for inspection.
Engine: Idling (after warming up)
Voltage between terminal EGRP and body earth.

OK: 2.0 V or higher

Q. Is the check result normal?

	Go to Step 5.

	Repair or replace the connector, or check and repair check harness between exhaust gas recirculation valve connector terminal and engine-ECU connector terminal EGRP. Check output line for open circuit and damage.