2012 Lexus IS FFACTORY OEM SERVICE PROCEDURE

DTC P0505: Idle Control System Malfunction: Procedure

  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0505) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Trouble Codes.
    5. Read the DTCs.

      Result

      Result Proceed to
      DTC P0505 is output A
      DTC P0505 and other DTCs are output B

      HINT: 

      If any DTCs other than P0505 are output, troubleshoot those DTCs first.

    B → See step   6 

    A: Go to next step 

  2. CHECK PCV HOSE CONNECTIONS 
    1. Check the PCV hose connections. Refer to ON-VEHICLE INSPECTION .

      OK

      PCV valve and hose are connected correctly and are not damaged.

    NG → REPAIR OR REPLACE PCV HOSE 

    OK: Go to next step 

  3. CHECK INTAKE SYSTEM 
    1. Check the intake system for vacuum leaks. Refer to ON-VEHICLE INSPECTION - Step 1 .

      OK

      No leaks from intake system.

    NG → REPAIR OR REPLACE INTAKE SYSTEM 

    OK: Go to next step 

  4. INSPECT THROTTLE BODY ASSEMBLY (THROTTLE VALVE) 
    1. Check the throttle body assembly condition.

      OK

      Throttle valve is not contaminated with foreign objects and moves smoothly.

    NG → See step   7 

    OK: Go to next step 

  5. CHECK WHETHER DTC OUTPUT RECURS (DTC P0505) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Clear the DTCs. Refer to DTC CHECK / CLEAR .
    5. Turn the engine switch off and wait for at least 30 seconds.
    6. Turn the engine switch on (IG).
    7. Turn the Techstream on.
    8. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.
    9. Enter the following menus: Powertrain / Engine / Trouble Codes.
    10. Read the pending DTCs.

      Result

      Result Proceed to
      DTC P0505 is output A
      DTC is not output B

    B → END 

    A → See step   8 

  6. GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART 
  7. REPLACE THROTTLE BODY ASSEMBLY. Refer to  REMOVAL 
  8. REPLACE ECM. Refer to  REMOVAL 
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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.