LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2023 >> RX 350h Premium >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Diagnostic Codes (P0335-P0420) >> SFI System >> DTC P0403-18: Exhaust Gas Recirculation "A" Circuit Current Below Threshold; DTC P0403-19: Exhaust Gas Recirculation "A" Circuit Current Above Threshold; DTC P1400-18: Exhaust Gas Recirculation "A" Control Circuit 2 Circuit Current Below Threshold; DTC P1400-19: Exhaust Gas Recirculation "A" Control Circuit 2 Circuit Current Above Threshold [10/2022 - 08/2023] >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P0403-18: Exhaust Gas Recirculation "A" Circuit Current Below Threshold; DTC P0403-19: Exhaust Gas Recirculation "A" Circuit Current Above Threshold; DTC P1400-18: Exhaust Gas Recirculation "A" Control Circuit 2 Circuit Current Below Threshold; DTC P1400-19: Exhaust Gas Recirculation "A" Control Circuit 2 Circuit Current Above Threshold [10/2022 - 08/2023]: Procedure

  1. PERFORM ACTIVE TEST USING GTS (CONTROL THE EGR STEP POSITION) 

    Pre-procedure1

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

      HINT: 

      The A/C switch and all accessory switches should be off.

      Powertrain > Engine > Data List 

      Tester Display
      Coolant Temperature
    • Confirm that the value of Data List item Engine Independent is "Operate" then check the value of Intake Manifold Absolute Pressure while performing the Active Test.

      Powertrain > Engine > Active Test 

      Active Test Display
      Control the EGR Step Position
      Data List Display
      Intake Manifold Absolute Pressure
      Engine Independent
      NOTE:
      • 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.

      OK

      The value of Intake Manifold Absolute Pressure changes in response to the EGR step position when the value of Engine Independent is "Operate".

      Standard

      - Control the EGR Step Position (Active Test)
      0 Steps 0 to 30 Steps
      Intake Manifold Absolute Pressure
      (Data List)
      (EGR valve is fully closed) Intake Manifold Absolute Pressure value is at least +10 kPa (1.45 psi) higher than when EGR valve is fully closed

      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.

      Result

      Result Proceed to
      Intake Manifold Absolute Pressure value is at least +10 kPa (1.45 psi) higher than when EGR valve is fully closed A
      None of the above conditions are met B

    Post-procedure1

    • None.

    Result: 

    CHECK FOR INTERMITTENT PROBLEMS. Refer to  CHECK FOR INTERMITTENT PROBLEMS [10/2022 - ] 

    Result: 

    See step  2

  2. INSPECT EGR VALVE ASSEMBLY 

    Refer to INSPECTION [10/2022 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE EGR VALVE ASSEMBLY. Refer to  REMOVAL [10/2022 - 08/2023] 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (EGR VALVE ASSEMBLY - ECM) 

    Pre-procedure1

    • Disconnect the EGR valve assembly connector.
    • Disconnect the ECM connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      B79-1 (EGA+) - B28-3 (EGA+) Always Below 1 Ω Ω
      B79-2 (EGA-) - B28-4 (EGA-) Always Below 1 Ω Ω
      B79-4 (EGB+) - B28-6 (EGB+) Always Below 1 Ω Ω
      B79-3 (EGB-) - B28-5 (EGB-) Always Below 1 Ω Ω
      B79-1 (EGA+) or B28-3 (EGA+) - Body ground and other terminals Always 10 kΩ or higher
      B79-2 (EGA-) or B28-4 (EGA-) - Body ground and other terminals Always 10 kΩ or higher
      B79-4 (EGB+) or B28-6 (EGB+) - Body ground and other terminals Always 10 kΩ or higher
      B79-3 (EGB-) or B28-5 (EGB-) - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None.

    Result: 

    OK 

    REPLACE ECM. Refer to  REMOVAL [10/2022 - 08/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR