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Home >> Toyota >> 2022 >> RAV4 LE, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 68 (Engine Control System (A25A-FKS) (W/ Canister Pump Module) - Diagnostic Codes (2 Of 7)) >> SFI SYSTEM (w/ Canister Pump Module) >> DTC P0128-00: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature); DTC P0128-07: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) Mechanical Failure [11/2018 - 08/2020] >> Procedure

DTC P0128-00: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature); DTC P0128-07: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) Mechanical Failure [11/2018 - 08/2020]: Procedure

WARNING: This page is about a different car, the 2020 Toyota RAV4 and 2019 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0128-00) 
    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.

      Powertrain > Engine > Trouble Codes 

      Result

      Result Proceed to
      DTC P0128-00 is output A
      DTC P0128-07 is output (w/ Grille Shutter System)
      DTC P0128-07 is output (w/o Grille Shutter System) B
      DTC P0128-00, P0128-07 and other DTCs are output C

      HINT: 

      If any DTCs other than P0128-00 or P0128-07 are output, troubleshoot those DTCs first.

    Result: 

    B 

    See step  6

    Result: 

    C 

    GO TO DTC CHART 

    Refer to DIAGNOSTIC TROUBLE CODE CHART [11/2018 - 10/2019] , or refer to DIAGNOSTIC TROUBLE CODE CHART [10/2019 - 08/2020]

    Result: 

    A 

    See step  2

  2. CHECK ENGINE COOLING SYSTEM 
    1. Check for defects in the engine cooling system that might cause the system to be too cold, such as abnormal cooling fan operation or any modifications.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE ENGINE COOLING SYSTEM 

    Result: 

    OK 

    See step  3

  3. INSPECT WATER INLET WITH THERMOSTAT SUB-ASSEMBLY 
    1. Inspect the water inlet with thermostat sub-assembly (thermostat opening temperature).

      Refer to INSPECTION [11/2018 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE WATER INLET WITH THERMOSTAT SUB-ASSEMBLY 

    Refer to REMOVAL [11/2018 - 10/2019] , or refer to REMOVAL [10/2019 - 08/2020]

    Result: 

    OK 

    See step  4

  4. INSPECT ENGINE COOLANT TEMPERATURE SENSOR 
    1. Inspect the engine coolant temperature sensor.

      Refer to INSPECTION [11/2018 - ]

      HINT: 

      Perform "Inspection After Repair" after replacing the engine coolant temperature sensor.

      Refer to INITIALIZATION [11/2018 - 10/2019] , or refer to INITIALIZATION [10/2019 - 08/2020]

      Result

      Result Proceed to
      OK (w/ Grille Shutter System) A
      OK (w/o Grille Shutter System) B
      NG C

    Result: 

    B 

    REPLACE ECM 

    Refer to REMOVAL [11/2018 - 08/2020]

    Result: 

    C 

    REPLACE ENGINE COOLANT TEMPERATURE SENSOR 

    Refer to REMOVAL [11/2018 - 08/2020]

    Result: 

    A 

    See step  5

  5. INSPECT NO. 2 ENGINE COOLANT TEMPERATURE SENSOR 
    1. Inspect the No. 2 engine coolant temperature sensor.

      Refer to PROCEDURE - Step 2

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE ECM 

    Refer to REMOVAL [11/2018 - 08/2020]

    Result: 

    NG 

    REPLACE NO. 2 ENGINE COOLANT TEMPERATURE SENSOR 

    Refer to REMOVAL [11/2018 - 08/2020]

  6. CHECK DTC OUTPUT (AUTOMATIC TRANSAXLE SYSTEM) 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to ON.
    3. Enter the following menus: Powertrain / Transmission / Trouble Codes.
    4. Check for DTCs.

      Powertrain > Transmission > Trouble Codes 

      HINT: 

      If DTCs related to the ATF temperature are output, troubleshoot those DTCs first.

      Result

      Result Proceed to
      No DTCs are output. A
      DTCs are output. B

    Result: 

    B 

    GO TO DTC CHART (AUTOMATIC TRANSAXLE SYSTEM) 

    Result: 

    A 

    See step  7

  7. INSPECT FLOW SHUTTING VALVE (FOR HEATER CONTROL) (WATER BY-PASS HOSE ASSEMBLY) 
    1. Cool the engine.
    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 / Active Test / Activate the Coolant Water Route Switching Valve / Data List / Engine Speed and Coolant Water Route Switching Valve.

      Powertrain > Engine > Active Test 

      Active Test Display
      Activate the Coolant Water Route Switching Valve
      Data List Display
      Engine Speed
      Coolant Water Route Switching Valve
    6. Perform the Active Test to close the flow shutting valve (for Heater Control).
    7. Start the engine.
    8. With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of 1500 rpm for 15 seconds.
    9. During the engine warm-up process, touch the flow shutting valve (for Heater Control) outlet and inlet hoses and check if there is a difference in temperature.

      OK

      There is a difference in temperature.

      HINT: 

      • P0128-07 may also be output if the flow shutting valve (for Heater Control) cannot fully close while the engine is cool.
      • If the flow shutting valve (for Heater Control) is closed during the engine warm-up process, there will be a difference in temperature between the outlet and inlet hoses.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FLOW SHUTTING VALVE (FOR HEATER CONTROL) (WATER BY-PASS HOSE ASSEMBLY) 

    Refer to REMOVAL [11/2018 - 10/2019] , or refer to REMOVAL [10/2019 - 08/2020]

    Result: 

    OK 

    See step  8

  8. INSPECT FLOW SHUTTING VALVE (FOR ATF CONTROL) (NO. 1 WATER BY-PASS HOSE) 
    1. Cool the engine.
    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 / Active Test / Activate the Coolant Water Route Switching Valve 2 / Data List / Engine Speed and Coolant Water Route Switching Valve 2.

      Powertrain > Engine > Active Test 

      Active Test Display
      Activate the Coolant Water Route Switching Valve 2
      Data List Display
      Engine Speed
      Coolant Water Route Switching Valve 2
    6. Perform the Active Test to close the flow shutting valve (for ATF Control).
    7. Start the engine.
    8. With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of 1500 rpm for 15 seconds.
    9. During the engine warm-up process, touch the flow shutting valve (for ATF Control) outlet and inlet hoses and check if there is a difference in temperature.

      OK

      There is a difference in temperature.

      HINT: 

      • P0128-07 may also be output if the flow shutting valve (for ATF Control) cannot fully close while the engine is cool.
      • If the flow shutting valve (for ATF Control) is closed during the engine warm-up process, there will be a difference in temperature between the outlet and inlet hoses.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    See step  2

    Result: 

    NG 

    REPLACE FLOW SHUTTING VALVE (FOR ATF CONTROL) (NO. 1 WATER BY-PASS HOSE) 

    Refer to REMOVAL [11/2018 - 10/2019] , or refer to REMOVAL [10/2019 - 08/2020]

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