DTC P0841: Transmission Fluid Pressure Sensor/Switch "A" Circuit Range/Performance: Notes

WARNING: This page is about a different variant/trim than selected.

DTC detecting condition:

Immediately at fault recognition

Trouble symptom:

Acceleration is poor during standing start.
Shift control malfunction
Engine speed increases abruptly.
CAUTION:
- Before performing diagnosis, record the freeze frame data.
- Use the check board when measuring the TCM terminal voltage and resistance.

Wiring diagram:

CVT control system Refer to WIRING SYSTEM>CVT CONTROL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

CHECK DTC.
Read the DTC using Subaru Select Monitor.

Are DTCs other than P0841 displayed?

Yes: Perform the diagnosis according to DTC. After the diagnosis, start the engine, and drive for 20 minutes in any driving pattern. (Include driving at a constant legal speed (for 20 seconds) at least once.) Read the DTC, and if P0841 alone is detected, Go to 2.

No: Go to 2.
CHECK INPUT SIGNAL FOR TCM.
1. Turn the ignition switch to ON.
2. Read the data of «secondary pressure sensor voltage.» using Subaru Select Monitor. (While shaking the secondary pressure sensor harness)
Is the value of «secondary pressure sensor voltage.» 0.39 - 0.61 V?

Yes: Go to 10.

No: Go to 3.
CHECK HARNESS.
1. Turn the ignition switch to OFF.
2. Disconnect the TCM connector.
3. Disconnect the secondary pressure sensor connector.
4. Measure the resistance between TCM connector and secondary pressure sensor connector.
  Connector & terminal
  
  (B54) No. 2 - (AT6) No. 3:
  
  (B54) No. 5 - (AT6) No. 2:
  
  (B54) No. 33 - (AT6) No. 1:
Is the resistance less than 1 Ω?

Yes: Go to 4.

No: Repair the open circuit of harness.
CHECK HARNESS.
Measure the resistance between TCM connectors.

Connector & terminal

(B54) No. 2 - (B54) No. 33:

(B54) No. 5 - (B54) No. 2:

(B54) No. 33 - (B54) No. 5:

Is the resistance 1 MΩ or more?

Yes: Go to 5.

No: Repair the short circuit of harness.
CHECK HARNESS.
Measure the resistance between TCM connector and transmission body.

Connector & terminal

(B54) No. 2 - Transmission body:

(B54) No. 5 - Transmission body:

(B54) No. 33 - Transmission body:

Is the resistance 1 MΩ or more?

Yes: Go to 6.

No: Repair the short circuit of harness.
CHECK POWER SUPPLY FOR SECONDARY PRESSURE SENSOR.
1. Turn the ignition switch to ON.
2. Measure the voltage between TCM connectors.
  Connector & terminal
  
  (B54) No. 33 (+) - (B54) No. 2 (-):
Is the voltage 4.6 - 5.4 V?

Yes: Go to 7.

No: Check for poor contact of connector, and if no fault is found, replace the TCM. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>TRANSMISSION CONTROL MODULE (TCM) .
CHECK POWER SUPPLY FOR SECONDARY PRESSURE SENSOR.
1. Turn the ignition switch to OFF.
2. Connect the secondary pressure sensor connector.
3. Turn the ignition switch to ON.
4. Measure the voltage between TCM connectors.
  Connector & terminal
  
  (B54) No. 33 (+) - (B54) No. 2 (-):
Is the voltage 4.6 - 5.4 V?

Yes: Go to 8.

No: Replace the secondary pressure sensor. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>SECONDARY PRESSURE SENSOR .
CHECK SECONDARY PRESSURE SENSOR OUTPUT.
Measure the voltage between TCM connectors.

Connector & terminal

(B54) No. 5 (+) - (B54) No. 2 (-):

Is the voltage 0.39 - 0.61 V?

Yes: Check for poor contact of connector, and if no fault is found, replace the TCM. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>TRANSMISSION CONTROL MODULE (TCM) .

No: Go to 9.
CHECK CONNECTOR.
1. Turn the ignition switch to OFF.
2. Disconnect the TCM connector.
3. Disconnect the secondary pressure sensor connector.
4. Check the TCM connector (B54) and the secondary pressure sensor connector (AT6).
Is there any fault in the TCM connector or the secondary pressure sensor connector?

Yes: Repair the connector, or replace harness.

No: Go to 10.
CHECK TRANSMISSION FLUID.
1. Connect all connectors.
2. Check the amount of ATF. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>ADJUSTMENT .
Is the ATF amount correct?

Yes: Go to 11.

No: Adjust the amount of ATF. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>ADJUSTMENT . Go to 11.
CHECK INPUT SIGNAL FOR TCM.
1. Perform the Clear Memory Mode.
2. Start the engine.
3. Warm up until the ATF temperature reaches to 40 - 70°C (104 - 158°F).
4. Depress the brake pedal and move the select lever to each range at an interval of five seconds.
  NOTE: Move the select lever in the following order: "P" → "R" → "N" → "D" → "N" → "R" → "P".
5. Stabilize the engine speed at idle.
6. Read the data of «Actual Secondary Pressure» using Subaru Select Monitor.
Is the «Actual Secondary Pressure» 0.5 - 1.5 MPa?

Yes: Go to 12.

No: Replace the secondary pressure sensor. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>SECONDARY PRESSURE SENSOR .
CHECK INPUT SIGNAL FOR TCM.
1. Shift the select lever to "P" range.
2. Keep the engine speed at 3, 000 rpm.
3. Read the data of «Actual Secondary Pressure» using Subaru Select Monitor.
Is the «Actual Secondary Pressure» 1.5 - 2.5 MPa? And is the difference of the actual oil pressure 0.2 MPa or more compared with the value measured in step 11?

Yes: Go to 13.

No: Replace the secondary pressure sensor. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>SECONDARY PRESSURE SENSOR .
CHECK FREEZE FRAME DATA.
1. Turn the ignition switch to OFF.
2. Check the recorded freeze frame data.
Was the detected symptom low-voltage malfunction? Refer to CONTINUOUSLY VARIABLE TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC P0841 TRANSMISSION FLUID PRESSURE SENSOR/SWITCH "A" CIRCUIT RANGE/PERFORMANCE>CLASSIFICATION OF SYMPTOM USING FREEZE FRAME DATA .

Yes: Replace the transmission assembly. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>AUTOMATIC TRANSMISSION ASSEMBLY .

No: Go to 14.
CHECK TCM INPUT SIGNAL (STALL TEST).
1. Lift up the vehicle.
2. Start the engine.
3. Apply the parking brake.
4. Set the select lever to "D" range.
5. Depress the brake pedal firmly.
6. Slowly open the accelerator fully, and stabilize the engine speed.
7. Read the data of «Actual Secondary Pressure» using Subaru Select Monitor.
Is the «Actual Secondary Pressure» 4.5 - 6.0 MPa?

Yes: Replace the transmission assembly. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>AUTOMATIC TRANSMISSION ASSEMBLY .

No: Go to 15.
CHECK TCM INPUT SIGNAL (STALL TEST).
Check the «Actual Secondary Pressure» in step 14.

Is the «Actual Secondary Pressure» 4.5 MPa or less?

Yes: Replace the transmission assembly. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>AUTOMATIC TRANSMISSION ASSEMBLY .

No: Replace the control valve body. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CONTROL VALVE BODY .