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Home >> Toyota >> 2015 >> Prius Four >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostic Codes (P0010-P0171)) (Except Plug-In) >> SFI System >> DTC P0101: Mass Air Flow Circuit Range / Performance Problem [08/2014 - ] >> Procedure
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DTC P0101: Mass Air Flow Circuit Range / Performance Problem [08/2014 - ]: Procedure

  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0101) 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
    5. Read the DTCs.

      Result

      Result Proceed to
      DTC P0101 is output A
      DTC P0101 and other DTCs are output B

      HINT: 

      If any DTCs other than P0101 are output, troubleshoot those DTCs first.

    B → See step   8 

    A: Go to next step 

  2. CHECK INTAKE SYSTEM 
    1. Check the intake system for vacuum leaks. Refer to ON-VEHICLE INSPECTION [08/2014 - ] .

      OK

      No leaks from the intake system.

      HINT: 

      Perform "Inspection After Repair" after repairing or replacing the intake system. Refer to INITIALIZATION [08/2014 - ] .

    NG → REPAIR OR REPLACE INTAKE SYSTEM 

    OK: Go to next step 

  3. CHECK PCV HOSE CONNECTIONS 
    1. Check the PCV hose connections.

      OK

      PCV hose is connected correctly and is not damaged.

    NG → REPAIR OR REPLACE PCV HOSE 

    OK: Go to next step 

  4. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE EGR STEP POSITION) 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Turn the Techstream on.
    4. Put the engine in inspection mode (maintenance mode). Refer to INSPECTION MODE PROCEDURE [08/2014 - ] .
    5. 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.

    6. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / Throttle Idle Position and MAP.
    7. Check that the Throttle Idle Position in ON and check the MAP values in the Data List while performing the Active Test.

      HINT: 

      • 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

      MAP change in response to EGR step position when Throttle Idle Position is ON in Data List.

      Standard

      - EGR Step Position (Active Test)
      0 Steps 0 to 30 Steps
      MAP
      (Data List)
      (EGR valve is fully closed) MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed

      HINT: 

      • While performing the Active Test, if the increase in the value of MAP is small, the EGR valve assembly may be a malfunctioning.
      • Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of MAP may occur while performing the Active Test. However, the amount that the value of MAP increases will be smaller than normal.

      Result

      Result Proceed to
      Outside of standard range A
      Within standard range B

    B → See step   6 

    A: Go to next step 

  5. INSPECT EGR VALVE ASSEMBLY 
    1. Remove the EGR valve assembly. Refer to REMOVAL [08/2014 - ] .
    2. Check if the EGR valve is stuck open.

      OK

      EGR valve is tightly closed.

      HINT: 

      Perform "Inspection After Repair" after replacing the EGR valve assembly. Refer to INITIALIZATION [08/2014 - ] .

    NG → See step   9 

    OK: Go to next step 

  6. REPLACE MASS AIR FLOW METER SUB-ASSEMBLY 
    1. Replace the mass air flow meter sub-assembly. Refer to REMOVAL [08/2014 - ] .

      HINT: 

      Perform "Inspection After Repair" after replacing the mass air flow meter sub-assembly. Refer to INITIALIZATION [08/2014 - ] .

    NEXT: Go to next step 

  7. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Turn the Techstream on.
    4. Clear the DTCs. Refer to DTC CHECK / CLEAR [08/2014 - ] .
    5. Turn the power switch off and wait for at least 30 seconds.
    6. Turn the power switch on (IG).
    7. Turn the Techstream on.
    8. Put the engine in inspection mode (maintenance mode). Refer to INSPECTION MODE PROCEDURE [08/2014 - ] .
    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 and ECT / Utility / All Readiness.
    12. Input the DTC: P0101.
    13. 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
      N/A
      • Unable to perform DTC judgment
      • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    NEXT → END 

  8. GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [08/2014 - ] 
  9. REPLACE EGR VALVE ASSEMBLY. Refer to  REMOVAL [08/2014 - ]