Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Evaporative Emission System Incorrect Purge Flow Actuator Stuck On (P04417E,P04417F,P04419C)

1. KEY-OFF MONITOR

   5 hours* after the engine switch is turned off, the electric leak detection pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.

   HINT:

   *: If the engine coolant temperature is not less than 35°C (95°F) 5 hours after the engine switch is turned off, the monitor check starts 2 hours later. If it is still not less than 35°C (95°F) 7 hours after the engine switch is turned off, the monitor check starts 2.5 hours later.

   Sequence	Operation	Description	Duration
   -	ECM activation	Activated by soak timer 5, 7 or 9.5 hours after engine switch turned off.	-
   A	Atmospheric pressure measurement	Vent valve is turned off (vent) and EVAP system pressure is measured by ECM in order to register atmospheric pressure. If pressure in EVAP system is not between 70 kPa(abs) and 110 kPa(abs) [10.15 psi(abs) and 15.95 psi(abs)], ECM cancels EVAP system monitor.	60 seconds
   B	First reference pressure measurement	In order to determine reference pressure, leak detection pump creates negative pressure (vacuum) through reference orifice and then ECM checks if leak detection pump and vent valve operate normally.	360 seconds
   C	EVAP system pressure measurement	Vent valve is turned on (closed) to shut EVAP system. Negative pressure (vacuum) is created in EVAP system, and EVAP system pressure is then measured. Write down measured value as it will be used in leak check. If EVAP pressure does not stabilize within 15 minutes, ECM cancels EVAP system monitor.	15 minutes*
   D	Purge VSV monitor	Purge VSV opened and then EVAP system pressure is measured by ECM. A large increase indicates normality.	10 seconds
   E	Second reference pressure measurement	After second reference pressure measurement, leak check is performed by comparing first and second reference pressure measurements. If stabilized system pressure is higher than second reference pressure, ECM determines that EVAP system leaking.	60 seconds
   -	Final check	Atmospheric pressure is measured and then monitoring result is recorded by ECM.	-

   *: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.

   

   *1	Purge VSV: Off (Closed)	*2	Purge VSV: On (Open)
   *3	Vent Valve: Off (Vent)	*4	Vent Valve: On (Closed)
   *5	Leak Detection Pump: Off	*6	Leak Detection Pump: On
   *7	Reference Orifice (0.02 inch)	*8	Canister Pressure Sensor
   *9	Canister	*10	Fuel Tank
   *11	Canister Pump Module	*12	Canister Filter
   *a	Operation A: Atmospheric Pressure Measurement	*b	Operation B, E: Reference Pressure Measurement
   *c	Operation C: EVAP System Pressure Measurement	*d	Operation D: Purge VSV Monitor
   *e	Atmospheric Pressure	*f	Negative Pressure

   1. Purge VSV stuck open

      In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The EVAP system pressure is then measured by the ECM using the canister pressure sensor. If the stabilized system pressure is higher than [second reference pressure x 0.2], the ECM interprets this as the purge VSV being stuck open. If any deterioration has occurred, the ECM will illuminate the MIL and store DTC P04417E (2 trip detection logic).

      
   2. Purge VSV stuck closed

      In operation D, the canister pressure sensor measures the EVAP (Evaporative Emission) system pressure. The pressure measurement for the purge VSV monitor begins when the purge VSV is turned on (open) after the EVAP leak check. When the measured pressure indicates an increase of 0.3 kPa(gauge) [0.044 psi(gauge)] or higher, the purge VSV is functioning normally. If the pressure does not increase, the ECM interprets this as the purge VSV being stuck closed, illuminates the MIL and store DTC P04417F (2 trip detection logic).

      
2. PURGE FLOW MONITOR

   The purge flow monitor consists of 2 monitors. The 1st monitor is conducted every time and the 2nd monitor is activated if necessary.

   

• The 1st monitor

  While the engine is running and the purge VSV is on (open), the ECM monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not created, the ECM begins the 2nd monitor.

• The 2nd monitor

  The vent valve is turned on (closed) and the EVAP pressure is then measured. If the variation in the pressure is less than 0.154 kPa(gauge) [0.022 psi(gauge)], the ECM interprets this as the purge VSV being stuck closed, illuminates the MIL and stores DTC P04419C (2 trip detection logic).

NOTICE:

• The Evaporative System Check (Automatic Mode) consists of 6 steps performed automatically by the Techstream. It takes a maximum of approximately 24 minutes.
• Do not perform the Evaporative System Check when the fuel tank is higher than 85% full because the cut-off valve may be closed, making the fuel tank leak check unavailable.
• Do not run the engine during this operation.
• When the temperature of the fuel is 35°C (95°F) or higher, a large amount of vapor forms and any check results become inaccurate. When performing the Evaporative System Check, keep the fuel temperature less than 35°C (95°F).

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.

  Click here

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

  Click here

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) [A].
7. Turn the Techstream on.
8. Enter the following menus: Powertrain / Engine / Utility / Evaporative System Check / Automatic Mode [B].
9. After the Evaporative System Check is completed, check for All Readiness by entering the following menus: Powertrain / Engine / Utility / All Readiness.
10. Input the DTC: P04417E or P04417F.
11. 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 is malfunctioning.
    • [A] to [B]: 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 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. Start the engine and wait 15 minutes or more [A].
7. Turn the Techstream on.
8. Enter the following menus: Powertrain / Engine / Trouble Codes [B].
9. 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.
10. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
11. Input the DTC: P04419C.
12. 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 is malfunctioning.
    • [A] to [B]: 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.

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