P0847: How to Diagnose & Fix — Transmission Fluid Pressure Sensor/Switch 'B' Circuit Low
2 vehicles · 2 makes · $150-$4,500 repair
How to diagnose and fix P0847: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Subaru Outback · 2010–2015
Early Lineartronic CVT Outbacks (2010-2015) have documented internal CVT failures — most commonly valve-body faults, but also chain/pulley and pressure-control problems — that can cause harsh or delayed engagement, RPM flare, jerking, limp mode, or complete loss of drive. Subaru extended the CVT powertrain warranty to 10 years / 100,000 miles on 2010-2015 Legacy/Outback 2.5L CVT and 2015 3.6L CVT models (and related models) under bulletin 16-107-17R, while stating the extension was not in response to a specific condition. A revised/upgraded valve body is installed at repair. This is separate from the low-speed torque-converter shudder complaint; here the transmission can set fault codes and go into failsafe. Out of warranty, a full CVT replacement is a multi-thousand-dollar repair.
Common Symptoms
- Harsh or delayed engagement into gear
- RPM flare / slipping under acceleration
- Jerking or shuddering
- Transmission warning light / limp mode
- Whining or loss of drive
How to Fix
If you experience harsh/delayed engagement, flaring, jerking, or a transmission warning, scan for CVT codes and get it evaluated quickly. First verify the vehicle is within (or was serviced under) the 10-year/100,000-mile CVT Warranty Extension — if so the valve-body or CVT repair should be free; escalate to Subaru of America if a dealer initially denies coverage, since owners report success on valve-body claims. Keep CVT fluid at the correct level/spec and address any leaks promptly, as low pressure accelerates valve-body wear. Out of warranty, a rebuilt/updated valve body is far cheaper than a complete CVT unit — get a diagnosis of the specific failed component before authorizing a full replacement.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Subaru 31706AA331 CVT Control Valve Body
early CVT valve body only after TCM diagnosis proves the valve-body fault Fitment/availability: 2010-2012 Outback 2.5-liter EJ253 CVT branch; confirm VIN and production date Fitment/availability: ships in 1-2 business days with Add to Ca…
- Genuine Subaru 31825AA055 CVT Control Valve Kit
later 2.5-liter CVT valve body only after TCM diagnosis proves the fault Fitment/availability: 2013-2015 Outback 2.5-liter FB25 CVT branch; current supersession of 31825AA050-054, confirm VIN Fitment/availability: Add to Cart live when r…
- Genuine Subaru 31706AA144 High-Torque CVT Control Valve Body
2015 3.6R high-torque CVT valve body after exact diagnosis and VIN selection Fitment/availability: 2015 Outback 3.6R CVT branch within this card; current supersession of production-specific 31706AA140/141, confirm VIN Fitment/availabilit…
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Sources for this issue (3)
Acura RDX · 2007–2012
The 2007-2012 RDX's 5-speed automatic uses clutch pressure switches to confirm hydraulic apply of the 2nd and 3rd clutch packs. These switches are a recurring failure point on the first-generation car — the 3rd clutch switch most often. When one fails or its circuit shorts, the PCM sets P0842/P0843 (2nd clutch switch) or P0847/P0848 (3rd clutch switch), and generic code readers may also show P0700, illuminating the check engine light and frequently the D light. The car may drop into a fail-safe gear pattern with harsh or limited shifting. This is an electrical/sensor failure, not internal clutch damage, and is regularly misquoted by shops as a transmission rebuild.
Common Symptoms
- Check engine light with P0700
- D indicator light blinking
- Harsh or limited shifting / fail-safe gear
- Loss of some forward gears
How to Fix
Scan the PCM's transmission codes with a Honda-capable tool (not just generic P0700) to identify which clutch pressure switch circuit is faulted. Inspect the connector and harness for oil wicking and corrosion first — a contaminated connector reproduces the same code. Replace the failed 2nd or 3rd clutch pressure switch (a screw-in switch on the transmission case) and change the fluid with genuine Honda ATF DW-1; do not substitute generic ATF, which degrades shift quality on this unit. No recall or warranty extension covers this.
Sources for this issue (4)
- P0847 — 3rd Clutch Transmission Fluid Pressure Switch Circuit Short B — AcuraZine 1G RDX Problems & Fixesforum
- Check Transmission Code P0842. Help? — AcuraZine 1G RDX Problems & Fixesforum
- Error Code PO842 — AcuraZine 1G RDX Problems & Fixesforum
- P0700 on Acura RDX: Transmission System Malfunction Guidearticle
Find P0847 by make
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P0847 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 P0847 mean?
P0847 stands for "Transmission Fluid Pressure Sensor/Switch 'B' Circuit Low." The transmission fluid pressure sensor/switch 'B' circuit voltage is below the expected range (too low / shorted to ground).
What are the most common causes of P0847?
The most common causes of P0847 are: Sensor signal shorted to ground, Faulty pressure sensor/switch B, Corroded/damaged connector, Internal TCM fault. The specific cause varies by vehicle.
How much does it cost to fix P0847?
Repair costs for P0847 range from $150 to $4,500, depending on the vehicle and root cause.
Which vehicles are affected by P0847?
Au7o has documented P0847 across 2 vehicle models from 2 manufacturers: Acura, Subaru.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.