DTC P0841 Diagnostics – 2012-2022 Subaru

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Bulletin Number: 16-102-16R; Revised: 10/13/21 Page 1 Continued… NUMBER: 16-102-16R DATE: 07/11/16 REVISED: 10/15/21 APPLICABILITY: Legacy & Outback 2010-19MY Equipped with CVT Forester 2014-22MY Equipped with CVT (Except Wilderness) Impreza 2012-22MY Equipped with CVT Crosstrek 2012-19MY Equipped with CVT WRX 2015-21MY Equipped with CVT SUBJECT: DTC P0841 Diagnostics INTRODUCTION: This Service Information bulletin provides a new flow chart and additional diagnostic tools to assist Technicians with troubleshooting DTC P0841- SECONDARY OIL PRESSURE SENSOR PERFORMANCE. SERVICE PROCEDURE / INFORMATION: The Diagnostic Flow Chart provided in this bulletin is quite extensive. To help make the chart more userfriendly, it has been broken down into 7 basic “Steps”. IMPORTANT NOTE: In some cases, it may not necessary to follow this flow chart in the specified order. For example: in a case where a whining sound concern is identified along with the DTC P0841, a Technician may feel performing pressure checks before beginning the electrical checks may be a way to expedite diagnosis of an internal hard part failure requiring transmission assembly replacement. • STEP 1- CVTF Fluid Condition Check • STEP 2- Customer Interview and DTC Confirmation • STEPS 3A and 3B- Check for Failure Caused by Electrical Wiring / Connection Issues • STEP 4- Check for Abnormal (Stuck) Sensor Output (Cannot Be Detected by Simply Switching Power ON) • STEP 5- Check the T/M Pressures Stored in the FFD • STEP 6- Determination of Appropriate Repair • STEP 7- Confirmation of Repair Use this Legend to help navigate the flow chart: SERVICE BULLETIN ATTENTION: GENERAL MANAGER q PARTS MANAGER q CLAIMS PERSONNEL q SERVICE MANAGER q IMPORTANT – All Service Personnel Should Read and Initial in the boxes provided, right. ©2016 Subaru of America, Inc. All rights reserved. Bulletin Number: 16-102-16R; Revised: 10/13/21 Page 2 DTC P0841- SECONDARY OIL PRESSURE SENSOR PERFORMANCE DIAGNOSTIC FLOW CHART STEPS 1 & 2: START Besides P0841, are any other DTCs stored (P0842, P0843, P0962 or P0963)? Yes Perform diagnosis of DTCs other than P0841. Conduct DRIVING CHECK North America: Perform DRIVE CYCLE D* *NOTE: Refer to Service Manual for all Drive Cycle procedures and details. Did P0841 reset? No Confirm whether P0841 is stored as a “Current” or “Past” DTC. Step 2- Customer Interview and DTC Confirmation Interview the customer using an interview form from the Service Manual. Save any stored FFD (Freeze Frame Data). Yes No Before proceeding, check color and smell (burnt?) and for contamination of CVTF to better assess condition of internal components. Step 1- CVTF Condition Check OK Replace T/M Assy. NG AA BB To Step 7 Continued… Bulletin Number: 16-102-16R; Revised: 10/13/21 Page 3 STEP 3A: •Is the voltage within specification? No No Problem in TCU 5V power supply circuit. Check the Secondary Oil Pressure Sensor voltage value using SSM, with the ign ON, engine OFF. Standard: 0.39～0.61(V), without abnormal fluctuation. （From this point on, every check should be conducted with and without wiggling the harness and / or related connectors). Disconnect the Secondary Oil Pressure Sensor connector [AT6], and TCU connector [T10]. Check the harness continuity using a DVOM: Measure Resistance Between: [T10-Pin33]～[AT6-Pin1] [T10-Pin5]～[AT6-Pin2] [T10-Pin2]～[AT6-Pin3] LESS THAN 1Ω [T10-Pin33]～[T10-Pin5] [T10-Pin5]～[T10-Pin2] [T10-Pin2]～[T10-Pin33] MORE THAN 1MΩ [T10-Pin33]～T/M case (GND) [T10-Pin5]～T/M case (GND) [T10-Pin2]～T/M case (GND) MORE THAN 1MΩ Steps 3A & 3B- Check for Failure Caused by Electrical Wiring / Connection Issues Connect “CHECK BOARD” (18460AA040) to TCU connector [T10]. Turn IG to ON, measure the Secondary Oil Pressure Sensor power supply voltage on [T10-Pin33～Pin2] using a DVOM with the Secondary Oil Pressure Sensor connector [AT6] disconnected. Standard: 4.6～5.4(V) without abnormal fluctuation. Is the sensor’s power supply voltage normal? Yes These are the checks for a suspected harness problem between the TCU and Secondary Oil Pressure Sensor. This is a check of the 5V power supply circuit to the Secondary Oil Pressure Sensor on the TCU side. Wiring harness has problem. Do the results show any harness problem? Yes Yes No NOTE: The wiring chart and connectors shown here are applicable to 2016MY Legacy/Outback, North American specification. Refer to applicable Service Manual for more details / information.. 3A BB CC BB DD EE Continued… Bulletin Number: 16-102-16R; Revised: 10/13/21 Page 4 STEP 3B: Replace Oil Pressure Sensor. Is the sensor’s power supply voltage normal? Yes Yes Is there any abnormality with connector [AT6] or [T10]？ Suspect Oil Pressure Sensor shorted internally. With the “CHECK BOARD” (18460AA040) connected to TCU connector [T10] and the Secondary Oil Pressure Sensor connector [AT6], disconnected, turn IG to ON, and measure the Secondary Oil Pressure Sensor power supply voltage at [T10-Pin 5～Pin 2] using a DVOM. Standard: 0.39～0.61(V) without abnormal fluctuation. Check the terminals of the Secondary Oil Pressure Sensor connector [AT6] or [T10] （Inspction point: Connector deformation, damage, or distortion). Connect the Secondary Oil Pressure Sensor connector [AT6] and “CHECK BOARD” (18460AA040) to TCU connector [T10] with IG ON. Measure the Secondary Oil Pressure Sensor power supply voltage on [T10-Pin33～Pin2] using a DVOM. Standard: 4.6～5.4(V) without abnormal fluctuation. Is the sensor’s power supply voltage normal? Yes Isolate location of harness problem. Isolate location of harness problem. Suspected malfunction of the Secondary Oil Pressure Sensor and / or Oil Pressure Sensor circuit. *No electrical malfunction is detected. Perform troubleshooting of P0841 again to confirm the problem is repaired. This is a check of the internal circuit of the Secondary Oil Pressure Sensor. Perform this check if the any connector terminals are excessively opened or loose (May not be found during continuity checks). Replace T/M wiring harness. Harness needs repair or replacement. It is suspected the TCU sensor signal input circuit has malfunction. Reason: The Secondary Oil Pressure Sensor output voltage is within the normal range but the sensor input voltage value is not. Suspect poor contact due to loose pin fit of connector terminal. No No No 3B BB CC DD BB EE Replace TCU. Continued… Bulletin Number: 16-102-16R; Revised: 10/13/21 Page 5 STEP 4: Adjust the fluid level to within specifications. Is fluid level full? No Check the CVT fluid level in preparation for Secondary Pressure check. Step 4- Check for Abnormal (Stuck) Sensor Output (Cannot Be Detected By Simply Switching Power ON) These (Tests A & B) are for identifying a stuck Secondary Pressure sensor output. Perform troubleshooting of P0841 again to confirm the problem is repaired. Replace Oil Pressure Sensor. Is difference between Test A & Test B within 0.2MPa.? Yes Test B- Check the Secondary Oil Pressure value with the following conditions: Warm-up the CVTF to around 60℃, turn IG OFF, then perform road test for DRIVE CYCLE A* again. After that, check & record the actual secondary pressure in P range at 3,000 rpm using SSM. Standard: 1.5MPa～2.5MPa, without abnormal fluctuation. Test A- Check the Secondary Oil Pressure with the engine idling. Warm up the CVTF to 60℃, turn IG to OFF then perform road test for DRIVE CYCLE A*. *NOTE: Refer to Service Manual for all Drive Cycle procedures and details. After that, check and record the actual secondary pressure in P range with the engine idling using SSM. Standard: 0.5MPa～1.5MPa, without abnormal fluctuation. Clear Memory if any DTC is stored. Suspect malfunction of Secondary Oil Pressure Sensor. No Yes BB BB Continued… Bulletin Number: 16-102-16R; Revised: 10/13/21 Page 6 STEPS 5 & 6: Is actual Secondary Pressure within specification? No Yes Suspect control valve assy. malfunction AND variator (pulley set) damage due to the instability of pressure adjustment. This is the test for a high pressure sticking malfunction of the presure adjustment circuit. This is the test for a high pressure malfunction. The pressure adjustment control keeps Secondary pressure high. In this case, the variator (pulley set) should not be damaged by chain slippage. Replace Control Replace T/M ASSY. Valve ASSY. Suspect oil pressure detection malfunction due to temporary pressure adjustment malfunction, or poor electrical contact. Replace T/M ASSY. Check the FFD recorded. （Refer to “How to identify the symptom causing P0841” in this TSB.) Does FFD recorded and / or mechanical gauge readings show low pressure failure? Yes Step 5- Check the T/M Fluid Pressures Stored In the FFD Has previous repair of the wiring or Sensor replacement been performed? Yes Is pressure below minimum standard value? Perform a stall test. Warm up the CVTF to 60℃ then perform stall test. Confirm and record the actual Secondary Pressure. Standard: 4.5～6MPa Clear Memory if any DTC is stored No No Yes No Step 6- Determination of Appropriate Repair DD DD BB BB CC CC BB Continued… Bulletin Number: 16-102-16R; Revised: 10/13/21 Page 7 STEP 7: Is P0841 still detected? END Currently normal condition Perform T/M Learning Procedure. Yes Currently abnormal Yes Road test vehicle and perform DRIVE CYCLE D *Refer to Service Manual for more details. Perform each check of P0841 diagnostics again. No No Step 7- Confirmation of Repair BB Any replacement of TCU, Control valve assy, T/M assy, T/M harness, or Secondary Oil Pressure sensor? Is P0841 still detected? END Currently normal condition Perform T/M Procedure. Yes Yes Road test vehicle and perform DRIVE CYCLE D *Refer to Service Manual for more details. Currently normal condition. P0841 is suspected to be stored along with other DTCs / problems. Perform P0841 No No Step 7- From AA of in Step 2 BB Any replacement of TCU, Control valve assy, T/M assy, T/M harness, or Secondary Oil Pressure sensor? • In addition to the flow chart, use the following slides and information for additional help with accurately diagnosing a P0841: TIP: Consider performing the pressure testing using a mechanical pressure gauge BEFORE electrical testing and compare the test results (between the gauge and SM4 displayed values). Both test results should be very close. If there is a significant discrepancy between them (e.g. the (known good) gauge results are significantly higher than the SM4-supplied values), the pressure sensor would be suspect. Continued… Bulletin Number: 16-102-16R; Revised: 10/13/21 Page 8 Additional Electrical Testing Information: • The following slides provide some additional pressure sensor and related wiring testing techniques, illustrations and photos. This information is intended to help Technicians make a more informed diagnosis of the root cause and required repairs. It will also help determine whether or not a terminal /pin connection is damaged and in need of repair or replacement: Precautions for Checking Transmission / Sensor Wiring: P0841 Wiring Check Points: Continued… Bulletin Number: 16-102-16R; Revised: 10/13/21 Page 9 Effects of Vibration on Connectors / Terminals: “Wiggle-Testing” Wiring: Continued… Bulletin Number: 16-102-16R; Revised: 10/13/21 Page 10 Check the Secondary Oil Pressure Sensor: Other Points to Inspect: Continued… Bulletin Number: 16-102-16R; Revised: 10/13/21 Page 11 Sliding Resistance Testing: Example of a Deformed Pin Terminal: Continued… Bulletin Number: 16-102-16R; Revised: 10/13/21 Page 12 CAUTION: VEHICLE SERVICING PERFORMED BY UNTRAINED PERSONS COULD RESULT IN SERIOUS INJURY TO THOSE PERSONS OR TO OTHERS. Subaru Service Bulletins are intended for use by professional technicians ONLY. They are written to inform those technicians of conditions that may occur in some vehicles, or to provide information that could assist in the proper servicing of the vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do the job correctly and safely. If a condition is described, DO NOT assume that this Service Bulletin applies to your vehicle, or that your vehicle will have that condition. SUBARU OF AMERICA, INC. IS ISO 14001 COMPLIANT ISO 14001 is the international standard for excellence in Environmental Management Systems. Please recycle or dispose of automotive products in a manner that is friendly to our environment and in accordance with all local, state and federal laws and regulations. Example of Incorrect Judgement of a Damaged or Deformed Pin Terminal: IMPORTANT REMINDERS: • SOA strongly discourages the printing and/or local storage of service information as previously released information and electronic publications may be updated at any time. • Always check for any open recalls or campaigns anytime a vehicle is in for servicing. • Always refer to STIS for the latest service information before performing any repairs.

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