1993 Subaru Justy BaseFACTORY OEM SERVICE PROCEDURE

Code 23: Pressure Sensor

NOTE: Refer to illustration for ECU connector and terminal identification. See Figure .
  1. Turn ignition off. Disconnect ECU connectors. Measure resistance between ECU and pressure sensor connectors. See the PRESSURE SENSOR RESISTANCE SPECIFICATIONS (TABLE 1)  table. If resistance is as specified, go to next step. If resistance is not as specified, repair connector and/or wiring harness as necessary.
    PRESSURE SENSOR RESISTANCE SPECIFICATIONS (TABLE 1)

    Measure Between Terminals Ohms
    No. 1 (1) & No. 2 (2) Less Than One
    No. 2 (1) & No. 2 (2) Less Than One
    No. 3 (1) & No. 1 (2) Less Than One
    No. 2 (3) & No. 3 (2) Less Than One
    (1) Measure at ECU connector F121.
    (2) Measure at pressure sensor connector. See Fig 1 .
    (3) Measure at ECU connector F119.
    Fig 1: Identifying Pressure Sensor Connector Terminals (Justy)
    G93E80683Courtesy of SUBARU OF AMERICA, INC.
  2. Reconnect ECU connectors. Measure resistance between terminals No. 1 and 2 and between terminals No. 3 and 2 of pressure sensor connector. See Fig 1 . If both resistances are infinite, go to next step. If either resistance is not infinite, repair connector and/or wiring harness as necessary.
  3. Turn ignition on. Measure voltage between terminals No. 2 and 3 of pressure sensor connector. See Fig 1 . If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECU.
  4. Reconnect pressure sensor connector. Turn ignition on. Backprobe ECU connector F121 and measure voltage between terminals No. 1 and 3 and between terminals No. 2 and 3. If both voltage readings are 3.4-3.8 volts, go to next step. If either voltage reading is not 3.4-3.8 volts, replace pressure sensor.
  5. Start engine. With engine idling, backprobe ECU connector F121 and measure voltage between terminals No. 1 and 3 and between terminals No. 2 and 3. If both voltage readings are 1.6-2.1 volts, replace ECU. If either voltage reading is not 1.6-2.1 volts, replace pressure sensor.
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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.