2009 Toyota Prius BaseFACTORY OEM SERVICE PROCEDURE

Inspection Procedure

HINT:

  • DTC P050B may be output when the engine has the symptoms listed below. If necessary, check the trouble areas listed below.
    SYMPTOM CHART

    Symptom Factor Trouble Area
    Low idle speed when engine is cold (immediately after engine start) Excessive engine friction
    • Engine oil deterioration
    • Drive belt tension
    • A/C compressor
    • Generator
    • P/S pump
    Rough idle when engine is cold (immediately after engine start) Abnormal combustion Fuel quality
  • 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.
  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P050B) 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to ON.
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Trouble Codes.
    5. Read the DTCs.

      Result 

      RESULT CHART

      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: GO TO  DIAGNOSTIC TROUBLE CODE CHART  

      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 / All Data / Short FT #1 and Long FT #1.
    5. Read the values displayed on the Techstream.
    6. Add together the Short FT #1 and Long FT #1 values to obtain the total fuel trim.

      OK: 

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

      NG: CHECK THROTTLE VALVE. Go to step   12 . 

      OK: Go to Next Step 

  3. PERFORM ACTIVE TEST USING TECHSTREAM (OPERATE OIL CONTROL VALVE) 
    1. Connect the Techstream to the DLC3.
    2. Start the engine and turn the Techstream on.
    3. Enter the following menus: Powertrain / Engine / Active Test / Control the VVT System (Bank 1) or Control the VVT System (Bank 2).
    4. Check the engine speed while operating the camshaft timing oil control valve using the Techstream.

      OK 

      TECHSTREAM OPERATION SPECIFIED CONDITION CHART

      Techstream Operation Specified Condition
      OFF Normal engine speed
      ON Engine Idles roughly or stalls (soon after camshaft timing oil control valve assembly switched from OFF to ON)

      NG: Go to step  8

      OK: Go to Next Step 

  4. CHECK PCV SYSTEM 

    OK: 

    The PCV hose is not pinched or damaged.  .

    NG: Go to step  9

    OK: Go to Next Step 

  5. CHECK INTAKE SYSTEM 
    1. Check the intake system for vacuum leakage.

      OK: 

      No leakage from the intake system  .

      NG: Go to step  10

      OK: Go to Next Step 

  6. 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: 

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

      NG: Go to step  11

      OK: Go to Next Step 

  7. REPLACE MASS AIR FLOW METER 
    1. Replace the mass air flow meter (See REMOVAL  ).

      NEXT: Go to step  15

  8. CHECK AND REPAIR VVT SYSTEM 

    NEXT: Go to step  15

  9. REPAIR OR REPLACE PCV SYSTEM 

    NEXT: Go to step  15

  10. REPAIR OR REPLACE INTAKE SYSTEM 

    NEXT: Go to step   15 

  11. REPLACE AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY 

    NEXT: Go to step  15

  12. INSPECT THROTTLE VALVE 
    1. Check that there are no deposits around the throttle valve.

      OK: 

      No deposits around the throttle valve  .

      NG: Go to step  14

      OK: Go to Next Step 

  13. REPLACE ECM 
    1. Replace the ECM (See REMOVAL  ).

      NEXT: Go to step  15

  14. REPAIR OR REPLACE THROTTLE BODY 

    NEXT: Go to next step 

  15. CHECK WHETHER DTC OUTPUT RECURS (DTC P050B) 
    NOTE: For this operation, the engine must be cold (the same temperature as the engine coolant temperature recorded in the freeze frame data).
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to ON.
    3. Turn the Techstream on.
    4. Clear the DTCs (See DTC CHECK / CLEAR  ).
    5. Start the engine and idle it for 1 minute.

      OK: 

      Stable fast idle  .

    6. Enter the following menus: Powertrain / Engine / Trouble Codes / Pending.
    7. Check for the pending DTCs.

      OK: 

      No pending DTC is output  .

      NEXT: REPAIR COMPLETED 

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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.