Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Catalyst System Efficiency Below Threshold Bank 1 (P042000,P043000)

NOTICE:

• If DTC P042000 is output, replace the exhaust manifold (*6) and the center exhaust pipe assembly (*10) together when catalyst replacement is necessary (Excluding air fuel ratio sensor*1 and heated oxygen sensor*3).
• If DTC P043000 is output, replace the exhaust manifold assembly LH (*7) and the center exhaust pipe assembly (*10) together when catalyst replacement is necessary (Excluding air fuel ratio sensor*2 and heated oxygen sensor*4).

HINT:

• It is necessary that the response of the heated oxygen sensor is normal in order to confirm DTCs P042000 and P043000. Therefore, perform the confirmation driving pattern for the heated oxygen sensor monitor before performing the drive pattern for the catalyst efficiency monitor.
• Performing this confirmation driving pattern will activate the catalyst efficiency monitor. This is very useful for verifying the completion of a repair.
• 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 engine 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 engine switch off and wait for at least 30 seconds.
6. Turn the engine switch on (IG).
7. Turn the Techstream on.
8. Enter the following menus: Powertrain / Engine / Monitor / Current Monitor.
9. Check that Catalyst Efficiency / Current is Incomplete.
10. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [A].
11. Drive the vehicle at approximately 60 km/h (37 mph) for 10 minutes or more [B].

    CAUTION:

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

    HINT:

    Drive the vehicle while keeping the engine load as constant as possible.

12. With the shift lever in M, drive the vehicle at 60 km/h (37 mph), and then decelerate the vehicle by releasing the accelerator pedal for 5 seconds or more to perform the fuel-cut [C].

    CAUTION:

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

13. Enter the following menus: Powertrain / Engine / Monitor / Current Monitor / O2 Sensor / RL F/C B1S2, RL F/C B2S2 [D].
14. Check the Test Value for RL F/C B1S2, RL F/C B2S2.
    • If Test Value displays a value larger than 0, perform the following procedure, as the O2 sensor monitor is finished.
    • If Test Value displays 0, perform step [C] until it displays a value larger than 0, as the O2 sensor monitor is not finished.
15. Turn the engine switch off and wait for at least 30 seconds [F].
16. Turn the engine switch on (IG).
17. Turn the Techstream on.
18. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [G].
19. Drive the vehicle at approximately 60 km/h (37 mph) for 10 minutes or more [H].

    CAUTION:

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

    HINT:

    • Drive the vehicle while keeping the engine load as constant as possible.
    • The monitor item will change to Complete as the Catalyst Efficiency monitor operates.
20. Enter the following menus: Powertrain / Engine / Trouble Codes [I].
21. Check if any DTCs are stored.

    HINT:

    • If the monitor item does not change to Complete, and no DTCs are stored, perform the following procedure.
    • [A] to [I]: 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 battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.
22. Drive the vehicle at a speed between 75 and 100 km/h (47 and 62 mph) for 10 minutes or more [J].

    CAUTION:

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

    HINT:

    • Drive the vehicle while keeping the engine load as constant as possible.
    • The monitor item will change to Complete as the Catalyst Efficiency monitor operates.
23. Enter the following menus: Powertrain / Engine / Trouble Codes [K].
24. Check if any DTCs are stored.

    HINT:

    If the monitor item does not change to Complete, and no DTCs are stored, drive the vehicle again under an increased load.

25. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
26. Input the DTC: P042000 or P043000.
27. 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.
    • [A] to [K]: 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 battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.

1. Connect the Techstream to the DLC3.
2. Turn the engine switch is on (IG) and turn the Techstream on [A].
3. Start the engine and warm it up with all the accessories switched off until the engine coolant temperature stabilizes [B].
4. Enter the following menus: Powertrain / Engine / Data List / A/F (O2) Sensor Voltage B1S1 and O2 Sensor Voltage B1S2 or A/F (O2) Sensor Voltage B2S1 and O2 Sensor Voltage B2S2.
5. Run the engine at an engine speed of between 2500 rpm and 3000 rpm for at least 3 minutes [C].
6. While running the engine at 3000 rpm for 2 seconds, and then 2000 rpm for 2 seconds, check the waveforms of the air fuel ratio and heated oxygen sensors using the Techstream [D].

HINT:

• If the voltage output of either the air fuel ratio or heated oxygen sensor does not fluctuate, or there is a noise in the waveform of either sensor, the sensor may be malfunctioning.
• If the voltage outputs of both the sensors remain lean or rich, the air fuel ratio may be extremely lean or rich. In such cases, perform the Control the Injection Volume for A/F Sensor Active Test using the Techstream.
• If the Three-way Catalytic Converter (TWC) has deteriorated, the heated oxygen sensor (located behind the Three-way Catalytic Converter [TWC]) voltage output fluctuates up and down frequently, even under normal driving conditions (active air fuel ratio control is not performed).

HINT:

• If a malfunction cannot be found when troubleshooting DTC P042000 or P043000, a lean or rich abnormality may be the cause. Perform troubleshooting by following the inspection procedure for P017100 or P017400 (System Too Lean), and P017200 or P017500 (System Too Rich).
• Bank 1 refers to the bank that includes the No. 1 cylinder*.

  *: The No. 1 cylinder is the cylinder which is farthest from the transaxle.

• Bank 2 refers to the bank that does not include the No. 1 cylinder.
• Sensor 1 refers to the sensor closest to the engine assembly.
• Sensor 2 refers to the sensor farthest away from the engine assembly.
• 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.

HINT:

• The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.
• Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
• The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.
• If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

• Lean: During Control the Injection Volume for A/F Sensor, the air fuel ratio sensor output voltage (A/F (O2) Sensor Voltage B1S1 or A/F (O2) Sensor Voltage B2S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2 Sensor Voltage B1S2 or O2 Sensor Voltage B2S2) is consistently less than 0.4 V.
• Rich: During Control the Injection Volume for A/F Sensor, the A/F (O2) Sensor Voltage B1S1 or A/F (O2) Sensor Voltage B2S1 is consistently less than 3.1 V, and the O2 Sensor Voltage B1S2 or O2 Sensor Voltage B2S2 is consistently higher than 0.55 V.
• Lean/Rich: During Control the Injection Volume for A/F Sensor of the Active Test, the output voltage of the air fuel ratio sensor or heated oxygen sensor alternates correctly.

NOTICE:

• If DTC P042000 is output, replace the exhaust manifold (TWC: Front catalyst) and the center exhaust pipe assembly (TWC: Rear catalyst) together when catalyst replacement is necessary.
• If DTC P043000 is output, replace the exhaust manifold assembly LH (TWC: Front catalyst) and the center exhaust pipe assembly (TWC: Rear catalyst) together when catalyst replacement is necessary.

Evaporative Emission System Leak Detection Reference Orifice Low Flow (P043E00,P043F00,P24007E,P24007F,P24187E)

Evaporative Emission System Incorrect Purge Flow Actuator Stuck On (P04417E,P04417F,P04419C)

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