Circuit/System Verification

Ignition ON.
Verify that DTCs P0556, P0557, or P0558 are not set.
- If the DTC is set
  Refer to DTC P0556, P0557, or P0558 .
- Go to next step: If the DTC is not set
Verify that the brake booster vacuum system has no damage, leakage or incorrect installation, refer to Brake Assist System Diagnosis
- If damage, leakage or incorrect installation is found
  Repair as necessary.
- Go to next step: If the inspection is OK
Test or replace the B19B Brake Booster Vacuum Sensor.
Verify the DTC does not set while operating the vehicle under the Conditions for Running the DTC.
- If the DTC sets
  Replace the Power Brake Booster.
- Go to next step: If the DTC does not set
All OK.