Transmission Fluid Pressure Sensor/Switch B Circuit Range/Performance
The P0846 code means the vehicle's onboard diagnostic system has detected: Transmission Fluid Pressure Sensor/Switch B Circuit Range/Performance. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $150 - $800 (parts and labor)
Read and clear transmission codes. Many trans codes are caused by low or burnt fluid -- check level and color before assuming the worst.
Basic scanners only read engine codes. This reads transmission, ABS, and airbag too.
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Common Symptoms
- Check Engine Light illuminated
- Shift quality degradation
- Slipping during gear changes
- Inconsistent transmission behavior
Probable Causes (Ranked by Likelihood)
- Pressure sensor B reading outside expected range Very High
- Degraded or contaminated transmission fluid High
- Partially blocked hydraulic passage Moderate
- Internal valve body wear Low
Common Fixes by Vehicle
What techs usually find when diagnosing P0846 on specific vehicles — tap your vehicle for the fix and the exact part:
Most makes with an electronically controlled automatic moderate DIY
P0846 means the transmission fluid pressure sensor/switch 'B' is reading implausibly - present, but not tracking what the control module expects. The two usual causes are the pressure switch/sensor itself and the electronic pressure control solenoid feeding it. Before either, check fluid level and condition: low, contaminated or overdue fluid produces genuine pressure readings that look like sensor faults, and no part fixes that. Symptoms are typically harsh, erratic or stuck shifting. If the fluid is burnt or the trans is slipping as well, the pressure reading may be reporting a real internal problem accurately. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 1-2 hoursFrequently Asked Questions
What causes range/performance issues on sensor B?
The sensor may be providing a voltage within the valid range but the pressure reading does not match what the TCM expects. Dirty fluid, a worn pump, or internal wear can all cause this.
Is a fluid change worth trying before replacing the sensor?
Yes, degraded fluid can cause abnormal pressure readings. A fluid and filter change is a good first step and is less expensive than sensor replacement.
Can P0846 and P0841 appear together?
Yes, if both sensors A and B show range/performance issues, the root cause may be a systemic problem like low fluid, a worn pump, or contaminated fluid rather than individual sensor failures.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Compare sensor B reading to actual pressure using a mechanical gauge
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Perform a transmission fluid and filter service
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Monitor sensor B data at various operating conditions
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Check for manufacturer TSBs for pressure sensor recalibration
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
Commonly Affected Vehicles
- 2007-2017 Nissan Altima (CVT)
- 2010-2020 Subaru Legacy (CVT)
- 2008-2018 Honda Pilot
- 2009-2019 Toyota Camry
Related Codes
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