P0841 on Subaru: How to Diagnose & Fix
Transmission Fluid Pressure Sensor/Switch "A" Circuit Range/Performance
1 Subaru model · 2 documented issues · 2 critical
P0841 on Subaru by model: symptoms, diagnosis and fix
A TCU programming error allows the Lineartronic CVT to engage before the drive chain is fully secured, causing chain slippage that fragments the chain guide. Owners report shudder, hesitation, irregular noises and MIL illumination; in worst cases chain breakage causes loss of motive power. This superseded the earlier WUV-07 recall and is the basis for the April 2024 class-action settlement covering 2019-2020 Ascents.
Common Symptoms
- shudder on acceleration
- hesitation
- whining or rattling from CVT
- CEL/MIL illuminated
- loss of forward propulsion
- P0700 / P2820-type codes
How to Fix
Verify recall WRK-21 / 21V-955 is completed at a Subaru dealer (free TCU reprogram, chain-slip data inspection, replacement of CVT if slippage is found, plus oil cooler add). Class-action settlement (final approval April 18, 2024) extends powertrain warranty to 8yr/100k for affected VINs and provides reimbursement vouchers ($400-$750) for prior repair attempts.
Sources for this issue (3)
On the 2019 Ascent the mid-joint of the transmission hydraulic pressure sensor harness was built with dissimilar metals - tinplate against copper. Galvanic action forms an oxide film at that joint, and the film corrupts the pressure signal the sensor sends to the TCU. When the sensor reports a pressure HIGHER than actual, the TCU commands the valve to reduce line pressure, and the Lineartronic's drive chain loses clamping tension. Slipping chain produces noise, vibration and hesitation, and continued driving in that state leads to loss of power. Recall population was 76,842 vehicles. This is a separate campaign and a separate root cause from the later TR690 chain-guide/TCU-programming recall (21V955 / WRK-21) - that one is a programming issue at clutch engagement, this one is a corroded sensor harness.
Common Symptoms
- Irregular noise from the transmission
- Vibration while driving
- Hesitation under acceleration
- Malfunction indicator lamp illuminated
- Loss of power if driven in the slipping condition
How to Fix
Free recall remedy under NHTSA 19V855 / Subaru campaign WUV-07. The base remedy is a TCU reprogram with more robust pressure-variation compensation. Vehicles found with specific stored diagnostic trouble codes also get the hydraulic sensor harness replaced. Any vehicle confirmed to have already run with low drive-chain tension gets a complete transmission assembly replacement, all at no charge. Because chain damage is cumulative, get the campaign done before symptoms appear - once the chain has slipped, a reprogram alone will not restore it.
Sources for this issue (4)
- NHTSA Part 573 Safety Recall Report 19V-855 (Subaru Ascent transmission hydraulic sensor)article
- Subaru Product Campaign Bulletin WUV-07 (recall 19V-855)article
- Safety Recall WUV-07 - CVT Chain Slip - 2019 Subaru Ascentarticle
- Subaru Ascent, Legacy, and Outback Recalled for Transmission Failure - Consumer Reportsarticle
P0841 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0841 mean on a Subaru?
P0841 stands for "Transmission Fluid Pressure Sensor/Switch "A" Circuit Range/Performance." This powertrain code means the transmission computer detected the 'A' transmission fluid pressure sensor or switch reading out of its expected range or not matching actual operating conditions. This sensor converts hydraulic line pressure into an electrical signal the computer uses to manage shift timing and quality. An out-of-range reading can cause incorrect shift behavior, harsh or slipping shifts, or limp mode. It should be addressed to prevent drivability problems and possible transmission damage. On Subaru it is documented across 1 model: Ascent.
What are the most common causes of P0841?
The most common causes of P0841 are: Low or contaminated transmission fluid, Faulty transmission fluid pressure sensor/switch, Wiring or connector problems in the sensor circuit, Clogged filter or restricted fluid passages, Worn valve body or internal pressure control fault, Faulty transmission control module (less common). The specific cause varies by vehicle.
How much does it cost to fix P0841 on a Subaru?
Repair costs vary widely with the root cause and Subaru model; each issue on this page carries its own estimate where one is published.
Looking for P0841 on a different make?
View P0841 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.