2021 Lexus RC F BaseFACTORY OEM SERVICE PROCEDURE

DTC U0300-51: Internal Control Module Software Incompatibility Not Programmed; DTC U0300-57: Internal Control Module Software Incompatibility Invalid/Incompatible Software Component [01/2023 - ]: Procedure

WARNING: This page is about a different car, the 2024 Lexus RC F and 2023 Lexus RC F. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK FOR DTCs 
    1. Check for DTCs.

      Powertrain > Engine > Trouble Codes 

      Result

      Result Proceed to
      SFI system DTC is not output A
      SFI system DTC is output B

    Result: 

    B 

    GO TO SFI SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [09/2014 - ] 

    Result: 

    A 

    See step  2

  2. CHECK FOR DTCs (HEALTH CHECK) 
    1. Using the Techstream, perform a health check.

      OK

      ECUs other than the forward recognition camera do not output specification information mismatch DTCs related to the ECM.

      Result

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

    Result: 

    B 

    REPLACE ECM. Refer to  REMOVAL [09/2014 - ] 

    Result: 

    A 

    See step  3

  3. READ VALUE USING TECHSTREAM 
    1. Using the Techstream, read the Data List.

      Chassis > Front Recognition Camera > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      HV/EV Equipped Information Vehicle information (engine) stored by forward recognition camera Non-HV/EV or HV/EV Non-HV/EV: Gasoline Model
      HV/EV: HV Model
      If a display different from vehicle specification is output, a forward recognition camera that was used with a different vehicle was installed, or the forward recognition camera may be malfunctioning.

      Chassis > Front Recognition Camera > Data List 

      Tester Display
      HV/EV Equipped Information

      HINT: 

      • When the specification stored by the forward recognition camera and the vehicle specification do not match, there is a malfunction in the specification information stored by the forward recognition camera. Therefore, replace the forward recognition camera.
      • When the specification stored by the forward recognition camera and the vehicle specification match, an ECM with different specifications may be installed. Therefore, replace the ECM.

      Result

      Result Proceed to
      Specification stored by the forward recognition camera and vehicle specification do not match A
      Specification stored by the forward recognition camera and vehicle specification match B

    Result: 

    A 

    REPLACE FORWARD RECOGNITION CAMERA. Refer to  REMOVAL [01/2023 - ] 

    Result: 

    B 

    REPLACE ECM. Refer to  REMOVAL [09/2014 - ] 

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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.