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HOMESERVICE MANUALSSUBARU2022IMPREZA BASE, 4D SEDAN, AUTOMATIC CVT TRANSREPAIR AND DIAGNOSIS (SINGLE PAGE)BRAKESTRACTION CONTROLELECTRIC BRAKE BOOSTER SYSTEM (DIAGNOSTICS)DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)DTC C1B4C SOLENOID VALVE 4 RANGE/PERFORMANCENOTES
2022 Subaru Impreza Base, 4D Sedan, Automatic CVT Trans

DTC C1B4C Solenoid Valve 4 Range/Performance: Notes

2022 Subaru Impreza Base, 4D Sedan, Automatic CVT TransSECTION Notes

1. - 

DTC detecting condition: 

  • DTC C1B4C (detail code: 75)

    When there is difference in electric current monitor cross check values inside IC.

  • DTC C1B4D (detail code: 72, 76)

    Solenoid valve 4 open circuit• Undercurrent state

  • DTC C1B4E (detail code: 71, 73, 74)

    Solenoid valve 4 circuit shorted•Overcurrent (low voltage state) electric current leaking state

Trouble symptom: 

  • Brake cannot be controlled.
  • Regenerative brake cannot be controlled.
  • Brake assist does not operate.
  • EyeSight functions (ACC/PCS) do not operate.
  1. CHECK DTC  .
    1. Using the Subaru Select Monitor, perform the clear memory of [Electric Brake Booster]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
    2. Read the DTC of [Electric Brake Booster] using the Subaru Select Monitor. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

    If DTCs C1B4C, C1B4D, C1B4E are not displayed, go to  A.

    If DTCs C1B4E (detail code: 73), C1C2E (detail code: 01) are displayed, go to  B.

    If DTCs C1B4C, C1B4D, C1B4E are displayed, go to  C.

    1. Currently, it is normal. Temporary interference from noise is a possible cause.
    2. Perform the diagnosis according to DTC C1C2E. Ref. to ELECTRIC BRAKE BOOSTER (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC C1C2E SOLENOID VALVE SUPPLY VOLTAGE LOW .
    3. Replace the brake booster assembly (with the master cylinder). Ref. to BRAKE>BRAKE BOOSTER .
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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.