P0843 on Acura: How to Diagnose & Fix
Transmission Fluid Pressure Sensor/Switch 'A' Circuit High
1 Acura model · 1 documented issue · $150-$500 repair
P0843 on Acura by model: symptoms, diagnosis and fix
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
P0843 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 P0843 mean on a Acura?
P0843 stands for "Transmission Fluid Pressure Sensor/Switch 'A' Circuit High." The transmission fluid pressure sensor/switch 'A' circuit voltage is above the expected range (too high / open or shorted to power). On Acura it is documented across 1 model: RDX.
What are the most common causes of P0843?
The most common causes of P0843 are: Sensor circuit open or shorted to voltage, Faulty pressure sensor/switch A, Corroded/damaged connector, Internal TCM fault. The specific cause varies by vehicle.
How much does it cost to fix P0843 on a Acura?
Published repair estimates on Acura range from $150 to $500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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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.