Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Exhaust Gas Recirculation "A" Low / Insufficient Flow (P04019C)

DESCRIPTION

Based on the driving conditions, the ECM regulates the volume of exhaust gas that is recirculated to each engine cylinder in order to lower the combustion temperature and reduce NOx emissions. The ECM monitors signals such as engine speed, engine coolant temperature, electric load, and vehicle speed. When the EGR permission conditions are met, the ECM controls the opening of the EGR valve linearly through signals to the EGR step motor.

MONITOR DESCRIPTION

The ECM monitors the pressure inside the intake manifold while opening and closing the EGR valve during fuel cut operation. If there is no change in the manifold absolute pressure sensor value, the ECM interprets this as a malfunction of the EGR valve assembly, illuminates the MIL and stores this DTC.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

MONITOR RESULT

Refer to detailed information in Checking Monitor Status.

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CONFIRMATION DRIVING PATTERN

HINT:

• After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.

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• When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.

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1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
5. Turn the power switch off and wait for at least 30 seconds.
6. Turn the power switch on (IG).
7. Turn the Techstream on.
8. Put the engine in Inspection Mode (Maintenance Mode).

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9. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher [A].
10. With the engine running, accelerate the vehicle to 65 km/h (40 mph) or more by depressing the accelerator pedal for at least 10 seconds [B].

    CAUTION:

    When performing the confirmation driving pattern, obey all speed limits and traffic laws.

    HINT:

    When accelerating the vehicle, depress the accelerator pedal more than normal to start the engine.

11. Idle the engine for 30 seconds or more [C].
12. With the shift lever in S and the engine running, accelerate the vehicle to 65 km/h (40 mph) or more [D].

    CAUTION:

    When performing the confirmation driving pattern, obey all speed limits and traffic laws.

    HINT:

    If the engine stops, further depress the accelerator pedal to restart the engine.

13. Perform the fuel cut operation for 5 seconds or more, with the accelerator pedal fully released [E].
14. Enter the following menus: Powertrain / Engine / Monitor / Current Monitor [F].
15. Check that Exhaust Gas Recirculation/VVT / Current is Complete.

    HINT:

    If the monitor item Exhaust Gas Recirculation/VVT / Current is Incomplete, perform the driving pattern again.

16. Enter the following menus: Powertrain / Engine / Monitor / Current Monitor / Exhaust Gas Recirculation/VVT / Details.
17. Check the Details (EGR FLOW INSUFFICIENCY).

    HINT:

    Make sure that the value is between MIN and MAX.

18. If the monitor item Exhaust Gas Recirculation/VVT / Current is still Incomplete, perform the following procedure.
19. Enter the following menus: Powertrain / Engine / Trouble Codes.
20. Read the pending DTCs.

    HINT:

    • If a pending DTC is output, the system is malfunctioning.
    • If a pending DTC is not output, perform the following procedure.
21. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
22. Input the DTC P04019C.
23. Check the DTC judgment result.

    Techstream Display	Description
    NORMAL	DTC judgment completed System normal
    ABNORMAL	DTC judgment completed System abnormal
    INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions

    HINT:

    • If the judgment result is NORMAL, the system is normal.
    • If the judgment result is ABNORMAL, the system has a malfunction.
    • If the judgment result is INCOMPLETE, perform the steps [A] through [F] again.
    • [A] to [F]: Normal judgment procedure.

      The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.

    • When clearing the permanent DTCs, do not disconnect the cable from the auxiliary battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.

WIRING DIAGRAM

Refer to DTC P040318.

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CAUTION / NOTICE / HINT

NOTICE:

• Vehicle Control History may be stored in the hybrid vehicle control ECU assembly if the engine is malfunctioning. Certain vehicle condition information is recorded when Vehicle Control History is stored. Reading the vehicle conditions recorded in both the Freeze Frame Data and Vehicle Control History can be useful for troubleshooting.

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  (Select Powertrain in Health Check and then check the time stamp data.)

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• If any "Engine Malfunction" Vehicle Control History item has been stored in the hybrid vehicle control ECU assembly, make sure to clear it. However, as all Vehicle Control History items are cleared simultaneously, if any Vehicle Control History items other than "Engine Malfunction" are stored, make sure to perform any troubleshooting for them before clearing Vehicle Control History.

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HINT:

• By using the Control the EGR Step Position Active Test, the operation of the EGR valve can be checked.
• If the EGR valve is normal and is opened using the Active Test, the Data List value changes as follows.

  Data List Item	Change in Data List when Number of Steps is Increased Using Control the EGR Step Position Active Test
  Intake Manifold Absolute Pressure	Pressure rises

• Read Freeze Frame Data using the Techstream. The ECM records vehicle and driving condition information as Freeze Frame Data the moment a DTC is stored. When troubleshooting, Freeze Frame Data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Trouble Codes.

(e) Read the DTCs.

HINT:

If any DTCs other than P04019C are output, troubleshoot those DTCs first.

B

GO TO DTC CHART

A

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Data List / Intake Manifold Absolute Pressure.

(e) Read the value of Intake Manifold Absolute Pressure.

Standard:

NG

REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR

OK

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Put the engine in Inspection Mode (Maintenance Mode).

(e) Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher.

HINT:

The A/C switch and all accessories should be off.

(f) Enter the following menus: Powertrain / Engine / Active Test / Control the EGR Step Position / Data List / Intake Manifold Absolute Pressure, Coolant Temperature and Engine Independent.

(g) According to the display on the Techstream, compare the values of Data List item Intake Manifold Absolute Pressure before and while performing the Active Test.

NOTICE:

• Make sure that the value of Data List item Engine Independent is "Operate" while performing the Active Test.
• Do not leave the EGR valve open for 10 seconds or more during the Active Test.
• Be sure to return the EGR valve to step 0 when the Active Test is completed.
• Do not open the EGR valve 30 steps or more during the Active Test.

Standard:

The value of Intake Manifold Absolute Pressure changes according to the EGR valve step set by the Active Test.

HINT:

• If the value of Data List item Engine Independent is "Not Opr" when the engine is idling, charge control is being performed. Perform the Active Test after charge control is complete ("Operate" is displayed).
• While performing the Active Test, if the increase in the value of Intake Manifold Absolute Pressure is small, the EGR valve assembly may be malfunctioning.
• Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of Intake Manifold Absolute Pressure may occur while performing the Active Test. However, the amount that the value of Intake Manifold Absolute Pressure increases will be smaller than normal.

B

GO TO STEP 6

C

GO TO STEP 12

A

(a) Check the intake system for vacuum leaks.

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OK:

No leaks from intake system.

HINT:

Perform "Inspection After Repair" after repairing or replacing the intake system.

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NG

REPAIR OR REPLACE INTAKE SYSTEM

OK

(a) Remove the EGR valve assembly.

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(b) Check if the EGR valve is stuck open.

OK:

EGR valve is tightly closed.

HINT:

Perform "Inspection After Repair" after replacing the EGR valve assembly.

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OK

REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR

NG

REPLACE EGR VALVE ASSEMBLY

(a) Replace the EGR valve assembly.

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HINT:

Perform "Inspection After Repair" after replacing the EGR valve assembly.

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NEXT

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Clear the DTCs.

(e) Turn the power switch off and wait for at least 30 seconds.

NEXT

(a) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

(b) Enter the following menus: Powertrain / Engine / Trouble Codes.

(c) Read the DTCs.

A

END

B

(a) Replace the EGR cooler assembly.

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HINT:

• If any of the EGR system related pipes (EGR pipe, exhaust manifold, etc.) are cracked, damaged or clogged, replace them as necessary.
• Perform "Inspection After Repair" after replacing the EGR system.

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NEXT

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Clear the DTCs.

(e) Turn the power switch off and wait for at least 30 seconds.

NEXT

(a) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

(b) Enter the following menus: Powertrain / Engine / Trouble Codes.

(c) Read the DTCs.

OK:

DTCs are not output.

NEXT

END

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Clear the DTCs.

(e) Turn the power switch off and wait for at least 30 seconds.

NEXT

(a) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

(b) Enter the following menus: Powertrain / Engine / Trouble Codes.

(c) Read the DTCs.

HINT:

Perform "Inspection After Repair" after replacing the EGR valve assembly.

Click here

A

END

B

REPLACE EGR VALVE ASSEMBLY