Code No. P0489: EGR Valve Position Sensor Circuit Low Input
OPERATION
- A power voltage of 5 V is applied to the EGR valve assembly power terminal from the engine-ECU connector terminal EGR5 and earthed to the engine-ECU connector terminal EGRE from the EGR valve assembly connector terminal.
- The sensor signal is inputted to the engine-ECU connector terminal EGRP from the EGR valve assembly output terminal.
FUNCTION
- The EGR valve assembly detects the position of the EGR valve and sends the signal to the engine-ECU.
- Based on the signal, the engine-ECU performs the feedback control of the EGR 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 EGR valve position sensor output voltage is 0.20 V or less.
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 position sensor
- Open/short circuit or harness damage in EGR valve position sensor circuit or loose connector contact
- Failed engine-ECU
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STEP 1. M.U.T.-III data list
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- Refer to Data List Reference Table
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- Item 16: EGR valve position sensor
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Q.
Is the check result normal?
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 Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).
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 Go to Step 2.
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STEP 2. Voltage measurement at EGR valve assembly connector (EGR5 line).
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(1)Use special tool test harness(MB991658) to connect connector and measure at pick-up harness.
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(3)Check the voltage between the EGR valve assembly connector (EGR5 line) and body earth.
OK: 4.9 - 5.1 V
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Q.
Is the check result normal?
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Go to Step 6.
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Go to Step 3.
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STEP 3. Voltage measurement at engine-ECU connector (EGR5 terminal).
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(1)Disconnect engine-ECU harness, and connect special tool power plant ECU check harness (MB992291) to measure at connector for inspection.
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(3)Check the voltage between the engine-ECU connector (EGR5 terminal) and body earth.
OK: 4.9 - 5.1 V
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Q.
Is the check result normal?
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Repair EGR5 line between EGR valve assembly connector and engine-ECU connector.
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Go to Step 4.
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STEP 4. Check of short to earth in EGR5 line between EGR valve assembly connector and engine-ECU connector.
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Q.
Is the check result normal?
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Go to Step 5.
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Repair the connector(s) or wiring harness.
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STEP 5. M.U.T.-III data list
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- Refer to Data List Reference Table .
- Item 16: EGR valve position sensor
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).
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Replace the engine-ECU.
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STEP 6. Resistance measurement at engine-ECU connector (EGRE terminal).
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(1)Disconnect the connector, and measure at the wiring harness side.
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(3)Measure the resistance between the engine-ECU connector (EGRE terminal) and body earth.
OK: Continuity (2 Ω or less)
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Q.
Is the check result normal?
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Go to Step 8.
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Go to Step 7.
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STEP 7. Check of damage in EGRE line between EGR valve assembly connector and engine-ECU connector.
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Q.
Is the check result normal?
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Go to Step 5.
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Repair the connector(s) or wiring harness.
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STEP 8. Voltage measurement at engine-ECU connector (EGRP terminal)
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(1)Use special tool test harness (MB991658) to connect connector and measure at pick-up harness.
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(2)Engine: Idling (after warming up)
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(3)Check the voltage between the engine-ECU connector (EGRP terminal) and body earth.
OK: 2.0 V or higher
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Q.
Is the check result normal?
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Go to Step 10.
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Go to Step 9.
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STEP 9. Check of short to earth in EGRP line between EGR valve assembly connector and engine-ECU connector.
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- Check output line for short circuit.
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Q.
Is the check result normal?
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Replace the EGR valve assembly.
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Repair the connector(s) or wiring harness.
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STEP 10. Voltage measurement at engine-ECU connector (EGRP terminal).
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(1)Disconnect engine-ECU harness, and connect special tool power plant ECU check harness (MB992291) to measure at connector for inspection.
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(2)Engine: Idling (after warming up)
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(3)Check the voltage between the engine-ECU connector (EGRP terminal) and body earth.
OK: 2.0 V or higher
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Q.
Is the check result normal?
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Go to Step 5.
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Repair EGRP line between EGR valve assembly connector and engine-ECU connector.
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