2011 Lexus IS FFACTORY OEM SERVICE PROCEDURE

DTC P050B: Cold Start Ignition Timing Performance: Procedure

  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P050B) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Trouble Codes.
    5. Read the DTCs.

      Result

      Result Proceed to
      DTC P050B is output A
      DTC P050B and other DTCs are output B

      HINT: 

      If any DTCs other than P050B are output, troubleshoot those DTCs first.

    B → See step   20 

    A: Go to next step 

  2. READ VALUE USING TECHSTREAM (FUEL TRIM) 

    HINT: 

    Calculate the total fuel trim values to check the characteristic deviation of the mass air flow meter.

    1. Connect the Techstream to the DLC3.
    2. Start the engine.
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Data List / A/F Control System / Short FT #1 and Long FT #1, or Short FT #2 and Long FT #2.
    5. Read the values displayed on the Techstream at engine idle.
    6. Add together the Short FT #1 and Long FT #1, or Short FT #2 and Long FT #2 values to obtain the total fuel trim.

      OK

      Total of Short FT #1 and Long FT #1, or Short FT #2 and Long FT #2 values is between -20% and 20%.

    NG → See step   5 

    OK: Go to next step 

  3. INSPECT THROTTLE BODY ASSEMBLY 
    1. Check for deposits around the throttle valve and check the throttle valve condition.

      OK

      No deposits around throttle valve and throttle valve moves smoothly.

      Result

      Result Proceed to
      NG A
      OK B

    B → See step   14 

    A: Go to next step 

  4. REPAIR OR REPLACE THROTTLE BODY ASSEMBLY 
    1. Repair or replace the throttle body assembly. Refer to REMOVAL .

    NEXT → See step   14 

  5. CHECK PCV HOSE (CONNECTIONS) 
    1. Check the PCV hose connections. Refer to ON-VEHICLE INSPECTION .

      OK

      PCV hose is connected correctly and is not damaged.

    NG → See step   10 

    OK: Go to next step 

  6. CHECK INTAKE SYSTEM 
    1. Check the intake system for vacuum leaks. Refer to ON-VEHICLE INSPECTION .

      OK

      No leaks in intake system.

    NG → See step   11 

    OK: Go to next step 

  7. INSPECT AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY 
    1. Visually check that the air cleaner filter element is not excessively contaminated with dirt or oil.

      OK

      Air cleaner filter element is not excessively contaminated with dirt or oil.

    NG → See step   12 

    OK: Go to next step 

  8. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE VVT-IE LINEAR) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG) and turn the Techstream on.
    3. Start the engine and warm it up.
    4. Enter the following menus: Powertrain / Engine / Active Test / Control the VVT-iE Linear (Bank 1) or Control the VVT-iE Linear (Bank 2) / VVT-iE Aim Angle #1 and VVT-iE Change Angle #1 or VVT-iE Aim Angle #2 and VVT-iE Change Angle #2.
    5. Perform the Active Test operation with the engine speed at 1500 RPM.

      OK

      Active Test Movement Order Difference between "VVT-iE Aim Angle" and "VVT Change Angle"
      0 deg → 10 deg → 20 deg → 40 deg → 10 deg → 0 deg → 10 deg → END Within 5 DegFR

    NG → See step   13 

    OK: Go to next step 

  9. READ VALUE USING TECHSTREAM (MAF) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Data List / All Data / MAF and Coolant Temp.
    5. Allow the engine to idle until Coolant Temp reaches 75°C (167°F) or higher.
    6. Read MAF with the engine speed at 3000 RPM.

      Standard

      Between 17 g/sec. and 23 g/sec. (shift lever: N; A/C: Off).

    OK → See step   14 

    NG → See step   15 

  10. REPAIR OR REPLACE PCV HOSE 
    1. Repair or replace the PCV hose.

    NEXT → See step   14 

  11. REPAIR OR REPLACE INTAKE SYSTEM 
    1. Repair or replace the intake system.

    NEXT → See step   14 

  12. REPLACE AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY 
    1. Replace the air cleaner filter element sub-assembly.

    NEXT → See step   14 

  13. CHECK AND REPAIR VVT SYSTEM 
    1. Check and repair the VVT system.

    NEXT: Go to next step 

  14. CHECK WHETHER DTC OUTPUT RECURS 
    NOTE:

    In this operation, the engine must be cold (approximately the same as the engine coolant temperature recorded in the freeze frame data).

    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Clear the DTCs. Refer to DTC CHECK / CLEAR .
    5. Turn the engine switch off.
    6. Turn the engine switch on (IG) and turn the Techstream on.
    7. Enter the following menus: Powertrain / Engine / Data List / Coolant Temp.
    8. Check that the engine coolant temperature is between -10°C and 60°C (14 and 140°F)
    9. Start the engine and warm it up.
    10. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    11. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
    12. Input the DTC: P050B.
    13. Check the DTC judgment result.
      RESULT

      Result Proceed to
      NORMAL (DTC is not output) A
      ABNORMAL (DTC P050B is output) B

    B → See step   15 

    A → See step   22 

  15. CHECK HARNESS AND CONNECTOR 
    1. Check the connection and terminal contact pressure of connectors and wire harnesses between the mass air flow meter and ECM. Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE .

      HINT: 

      Repair any problems.

    NEXT: Go to next step 

  16. CHECK WHETHER DTC OUTPUT RECURS 
    NOTE:

    In this operation, the engine must be cold (approximately the same as the engine coolant temperature recorded in the freeze frame data).

    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Clear the DTCs. Refer to DTC CHECK / CLEAR .
    5. Turn the engine switch off.
    6. Turn the engine switch on (IG) and turn the Techstream on.
    7. Enter the following menus: Powertrain / Engine / Data List / Coolant Temp.
    8. Check that the engine coolant temperature is between -10°C and 60°C (14 and 140°F)
    9. Start the engine and warm it up.
    10. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    11. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
    12. Input the DTC: P050B.
    13. Check the DTC judgment result.
      RESULT

      Result Proceed to
      ABNORMAL (DTC P050B is output) A
      NORMAL (DTC is not output) B

    B → END 

    A: Go to next step 

  17. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM) 
    1. Disconnect the mass air flow meter connector.
    2. Disconnect the ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance (Check for Open)

      Tester Connection Condition Specified Condition
      E3-25 (VG) - E29-5 (VG) Always Below 1 Ω
      E3-24 (E2G) - E29-4 (E2G) Always Below 1 Ω

      Standard resistance (Check for Short)

      Tester Connection Condition Specified Condition
      E3-25 (VG) or E29-5 (VG) - Body ground Always 10 kΩ or higher
    4. Reconnect the mass air flow meter connector.
    5. Reconnect the ECM connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  18. REPLACE MASS AIR FLOW METER ASSEMBLY 
    1. Replace the mass air flow meter assembly. Refer to REMOVAL .

      HINT: 

      If the result of the inspection performed in step 9 indicated no problem, proceed to the next step without replacing the mass air flow meter assembly.

    NEXT: Go to next step 

  19. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED 
    NOTE:

    In this operation, the engine must be cold (approximately the same as the engine coolant temperature recorded in the freeze frame data).

    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Clear the DTCs. Refer to DTC CHECK / CLEAR .
    5. Turn the engine switch off.
    6. Turn the engine switch on (IG) and turn the Techstream on.
    7. Enter the following menus: Powertrain / Engine / Data List / Coolant Temp.
    8. Check that the engine coolant temperature is between -10°C and 60°C (14 and 140°F)
    9. Start the engine and warm it up.
    10. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    11. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
    12. Input the DTC: P050B.
    13. Check the DTC judgment result.
      RESULT

      Result Proceed to
      NORMAL (DTC is not output) A
      ABNORMAL (DTC P050B is output) B

    B → See step   21 

    A → END 

  20. GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART 
  21. REPLACE ECM. Refer to  REMOVAL 
  22. CHECK FOR INTERMITTENT PROBLEMS. Refer to  CHECK FOR INTERMITTENT PROBLEMS 
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.