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Home >> Toyota >> 2019 >> Sequoia SR5, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 17 (Engine Control System (3UR-FBE) - Diagnostic Codes (2 Of 6)) >> SFI System >> DTC P0171: System Too Lean (Bank 1); DTC P0172: System Too Rich (Bank 1); DTC P0174: System Too Lean (Bank 2); DTC P0175: System Too Rich (Bank 2) [08/2015 - 08/2018] >> Procedure

DTC P0171: System Too Lean (Bank 1); DTC P0172: System Too Rich (Bank 1); DTC P0174: System Too Lean (Bank 2); DTC P0175: System Too Rich (Bank 2) [08/2015 - 08/2018]: Procedure

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  1. CHECK FOR ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0171, P0172, P0174 OR P0175) 
    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 and ECT / Trouble Codes.
    5. Read DTCs.
      RESULT

      Result Proceed to
      P0171, P0172, P0174 or P0175 is output A
      P0171, P0172, P0174 or P0175 and other DTCs are output B

      HINT: 

      If any DTCs other than P0171, P0172, P0174 or P0175 are output, troubleshoot those DTCs first.

    Result: 

    B 

    GO TO DTC CHART 

    Refer to:

    DIAGNOSTIC TROUBLE CODE CHART [08/2015 - 10/2016]

    DIAGNOSTIC TROUBLE CODE CHART [10/2016 - 08/2017]

    DIAGNOSTIC TROUBLE CODE CHART [08/2017 - 08/2018]

    Result: 

    A 

    See step  2

  2. READ VALUE USING TECHSTREAM (ALCOHOL DENSITY ESTIMATE, SHORT FT, LONG FT) [STEP *1] 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to ON.
    3. Turn the Techstream on.
    4. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    5. Make sure that the Data List item "Alcohol Density Learning" is "Compl".
    6. Enter the following menus: Powertrain / Engine and ECT / Data List / Alcohol Density Estimate, Short FT and Long FT.
    7. Check the data list values, and then write them down.

    Result: 

    NEXT 

    See step  3

  3. CONFIRM ALCOHOL CONCENTRATION IN FUEL [STEP *2] 
    1. Confirm the alcohol concentration in the fuel (Refer to PROCEDURE - Step 4 ).
    2. Write down the alcohol concentration in the fuel.

    Result: 

    NEXT 

    See step  4

  4. CONFIRM LEARNED VALUE 
    1. Use the following formula to calculate the difference between the learned values from step *1 and the actual alcohol concentration in the fuel from step *2.

      HINT: 

      [ ((Alcohol Density Estimate / 2) + Short FT + Long FT) - (Alcohol Concentration in Fuel / 2) ] < 35%

      RESULT

      Result Proceed to
      Difference is 35% or more A
      Difference is less than 35% B

    Result: 

    B 

    See step  6

    Result: 

    A 

    See step  5

  5. CHECK FUEL INJECTION SYSTEM 
    1. Check the fuel injection system (Refer to Fuel Injection System [08/2015 - 08/2017] , or refer to Fuel Injection System [08/2017 - 08/2018] ).

      HINT: 

      If the problem area cannot be determined by checking the fuel injection system, proceed to the next step.

    Result: 

    NEXT 

    See step  9

  6. CONFIRM LEARNED VALUE 
    1. Use the following formula to calculate the difference between the learned value from step *1 and the actual alcohol concentration in the fuel from step *2.

      HINT: 

      [ (Alcohol Density Estimate / 2) - (Alcohol Concentration in Fuel / 2) ] < 10%

      RESULT

      Result Proceed to
      Difference is 10% or more A
      Difference is less than 10% B

    Result: 

    B 

    See step  9

    Result: 

    A 

    See step  7

  7. CONFIRM ALCOHOL CONCENTRATION IN FUEL 
    1. Confirm the actual alcohol concentration in the fuel from step *2.
      RESULT

      Result Proceed to
      Alcohol concentration is 20% or less A
      Alcohol concentration is more than 20% B

    Result: 

    A 

    See step  10

    Result: 

    B 

    See step  8

  8. REPLACE FUEL 
    1. Replace the fuel with E0 gasoline (replace approximately 20 liters (5 gallons) of fuel).
    2. Connect the Techstream to the DLC3.
    3. Turn the ignition switch to ON.
    4. Turn the Techstream on.
    5. Enter the following menus: Powertrain / Engine and ECT / Utility / Fuel Density Learning Value Reset.
    6. Confirm the following conditions as instructed on the screen.
      1. Ignition switch: ON
      2. Engine: stopped
      3. Battery voltage: 9 V or higher
    7. After confirming, select "Next" and initialize the learned value.

      HINT: 

      If a message indicating learned value initialization failure is displayed on the screen, confirm the execution conditions, and perform learned value initialization again.

    8. Turn the ignition switch off and wait for at least 30 seconds.
      NOTE:

      Proceed to the next step without starting the engine after performing "Learning Value Reset".

    Result: 

    NEXT 

    See step  10

  9. ADD FUEL 
    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 and ECT / Utility / Fuel Density Learning Value Reset.
    5. Confirm the following conditions as instructed on the screen.
      1. Ignition switch: ON
      2. Engine: stopped
      3. Battery voltage: 9 V or higher
    6. After confirming, select "Next" and initialize the learned value.

      HINT: 

      If a message indicating learned value initialization failure is displayed on the screen, confirm the execution conditions, and perform learned value initialization again.

    7. Turn the ignition switch off and wait for at least 30 seconds.
    8. Add at least 8 liters (2 gallons) of fuel.

      HINT: 

      Check "Fuel Remaining Volume" in the Data List and if it has a value of 85% or more, remove enough fuel so that the value decreases to less than 85% before adding fuel.

    9. Turn the ignition switch to ON.
    10. Enter the following menus: Powertrain / Engine and ECT / Data List / Alcohol Density learning.
    11. Make sure that the Data List item "Alcohol Density Learning" is "Incmpl".

    Result: 

    NEXT 

    See step  11

  10. PERFORM INITIALIZATION (FUEL DENSITY LEARNING VALUE RESET) 
    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 and ECT / Utility / Fuel Density Learning Value Reset.

      HINT: 

      • After clearing the learned value, the engine may become difficult to start if the concentration of alcohol in the fuel is high. Therefore, it may be necessary to crank the engine a few times before it starts.
      • If "Fuel Density Learning Value Reset" is performed after warming the engine coolant up to approximately 50°C (122°F), the engine becomes easier to start afterward.
    5. Confirm the following conditions as instructed on the screen.
      1. Ignition switch: ON
      2. Engine: stopped
      3. Battery voltage: 9 V or higher
    6. Press "Next".
    7. When "Next" is pressed, initialization is performed automatically.
    8. Turn the ignition switch off.
    9. Add at least 8 liters (2 gallons) of fuel.
      NOTE:

      Add fuel immediately after resetting. (Do not start the engine before adding fuel.)

      HINT: 

      • Learning of the alcohol concentration will not be started until the ECM judges that the fuel gauge has moved after resetting. Add at least 8 liters (2 gallons) of fuel.
      • Check "Fuel Remaining Volume" in the Data List and if it has a value of 85% or more, remove enough fuel so that the value decreases to less than 85% before adding fuel.
    10. Turn the ignition switch to ON.
    11. Enter the following menus: Powertrain / Engine and ECT / Data List / Alcohol Density learning.
    12. Make sure that the Data List item "Alcohol Density Learning" is "Incmpl".

    Result: 

    NEXT 

    See step  11

  11. CONFIRM LEARNED VALUE 

    HINT: 

    If the difference between the learned value of the vehicle from step *1 and the actual alcohol concentration in the fuel from step *2 is less than 10%, it is not necessary to perform learning.

    1. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    2. Make sure that the Data List item "Alcohol Density Learning" is "Compl".
    3. Enter the following menus: Powertrain / Engine and ECT / Data List / Alcohol Density Estimate, Short FT and Long FT.
    4. Check the data list values, and then write them down.
    5. Confirm the alcohol concentration in the fuel (Refer to PROCEDURE - Step 4 ).
    6. Write down the alcohol concentration in the fuel.
    7. Use the following formula to calculate the difference between the current learned value and the actual alcohol concentration in the fuel.

      HINT: 

      [ (Alcohol Density Estimate / 2) - (Alcohol Concentration in Fuel / 2) ] < 10%

      OK

      Result Specified Condition
      Difference between actual alcohol concentration and Alcohol Density Estimate Less than 10%
      Short FT and Long FT Between -35% and 35%

    Result: 

    OK 

    END 

    Result: 

    NG 

    See step  2

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