2008 Toyota Prius BaseFACTORY OEM SERVICE PROCEDURE

Inspection Procedure

  1. INSPECT FOR EXHAUST GAS LEAK 
    1. Allow the engine to idle.
    2. Check for exhaust gas leaks around the heated oxygen sensor.

      OK: 

      No leakage from the heated oxygen sensor. 

    NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT 

    OK: Go to next step 

  2. CHECK HEATED OXYGEN SENSOR 
    1. Connect Techstream to the DLC3.
    2. Start the engine and turn the tester on.
    3. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
    4. Select the following menu items: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
    5. Perform the Control the Injection Volume for A/F Sensor operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
    6. Monitor the voltage outputs of the HO2 sensors (O2S B1S2) displayed on the tester.

      HINT:

      • The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
      • Each sensor reacts in accordance with increases in the fuel injection volume.

      Standard voltage 

      VOLTAGE SPECIFICATION

      Tester Display (Sensor) Injection Volumes Voltages
      O2S B1S2 -12.5% Less than 0.4 V
      +25% More than 0.5 V

    NG: REPLACE HEATED OXYGEN SENSOR 

    Fig 1: Voltage And Fuel-Trim Percentage Graph
    G04996382Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next step 

  3. CHECK WHETHER DTC OUTPUT RECURS (DTC P0606) 
    1. Connect Techstream to the DLC3.
    2. Turn the power switch ON (IG) and turn the tester on.
    3. Clear the DTC (See DTC CHECK / CLEAR  ).
    4. Turn the power switch OFF and turn the tester off.
    5. Disconnect the battery negative terminal and wait for 1 minute.
    6. Connect the battery negative terminal.
    7. Start the engine.
    8. Perform the drive pattern.
      1. Warm up the engine.
      2. Accelerate the vehicle to 50 mph (80 km/h) and stop the vehicle.
      3. Drive the vehicle at 35 to 50 mph (60 to 80 km/h) for 5 minutes or more.
    9. Turn the tester on.
    10. Select the following menu items: Powertrain / Engine and ECT / Trouble Code.
      Fig 2: Engine Coolant Temperature Graph
      G04996383Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    11. Read the DTCs.

      Result 

      RESULT CHART

      Display (DTC output) Proceed to
      P0606 A
      No output B

    B: CHECK FOR INTERMITTENT PROBLEMS 

    A: REPLACE ECM 

Factory Service Tools

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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.

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