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HOMESERVICE MANUALSSUBARU2022IMPREZA BASE, 4D SEDAN, AUTOMATIC CVT TRANSREPAIR AND DIAGNOSISTRANSMISSIONAUTOMATIC TRANSAUTOMATIC TRANSAXLE (DIAGNOSTICS)DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)DTC P0842: TRANSMISSION FLUID PRESSURE SENSOR/SWITCH "A" CIRCUIT LOWNOTES
2022 Subaru Impreza Base, 4D Sedan, Automatic CVT Trans

DTC P0842: Transmission Fluid Pressure Sensor/Switch "A" Circuit Low: Notes

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

1. - 

DTC detecting condition: 

Immediately at fault recognition

Trouble symptom: 

Shift characteristics malfunction

Wiring diagram: 

CVT control system Ref. to WIRING SYSTEM (IMPREZA MODEL)>CVT CONTROL SYSTEM .

G10276512Courtesy of SUBARU OF AMERICA, INC.
CAUTION:
  1. CHECK INPUT SIGNAL FOR TCM  .
    1. Start the engine.
    2. Warm up until the ATF temperature reaches to 40 - 70°C (104 - 158°F).
    3. Depress the brake pedal, and shift the select lever to "D" range.
    4. Shift the select lever to "P" range.
    5. Stabilize the engine speed at idle.
    6. Using the Subaru Select Monitor, read data of [Actual Secondary Pressure] in the [Data Monitor] of [Transmission]. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>DATA MONITOR .

    Is [Actual Secondary Pressure] 0.5 - 1.5 MPa?

    Yes:  Check for poor contact of connector.

    No:  Go to  2.

  2. CHECK HARNESS  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the TCM connector.
    3. Disconnect the transmission connector.
    4. Measure the resistance between TCM connector and transmission connectors.

      Connector & terminal 

      (T10) No. 2 - (AT6) No. 3:

      (T10) No. 5 - (AT6) No. 2:

      (T10) No. 33 - (AT6) No. 1:

    Is the resistance less than 1 Ω?

    Yes:  Go to  3.

    No:  Repair the open circuit of harness.

  3. CHECK HARNESS  .

    Measure the resistance between TCM connector and chassis ground.

    Connector & terminal 

    (T10) No. 5 - Chassis ground:

    (T10) No. 33 - Chassis ground:

    Is the resistance 1 MΩ or more?

    Yes:  Go to  4.

    No:  Repair the short circuit of harness.

  4. CHECK POWER SUPPLY FOR SECONDARY PRESSURE SENSOR  .
    1. Connect the TCM connector.
    2. Turn the ignition switch to ON.
    3. Measure the voltage between secondary pressure sensor connector terminals.

      Connector & terminal 

      (AT6) No. 1 (+) - (AT6) No. 3 (-):

    Is the voltage 4.5 V or more?

    Yes:  Replace the secondary pressure sensor. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>SECONDARY PRESSURE SENSOR . If the replacement of the sensor do not eliminate the malfunction, replace the TCM. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>TRANSMISSION CONTROL MODULE (TCM) .

    No:  Check for poor contact of connector, and if no fault is found, replace the TCM. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>TRANSMISSION CONTROL MODULE (TCM) .

RENDER: 1.0x

NO RELATED

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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.