Transmission Fluid Pressure Sensor/Switch B Circuit Low
The P0847 code means the vehicle's onboard diagnostic system has detected: Transmission Fluid Pressure Sensor/Switch B Circuit Low. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $100 - $500 (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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What Are the Symptoms of P0847?
- Check Engine Light illuminated
- Transmission slipping or flaring between gears
- Soft or delayed shifts
- Possible limp mode activation
What Causes P0847? (Most Likely First)
- Short to ground in pressure sensor B signal wire Very High
- Faulty pressure sensor B producing low voltage High
- Corroded connector at sensor B Moderate
- Very low transmission fluid level Moderate
Can I Still Drive with P0847?
Short distances only. P0847 is rated moderate severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
Should I check the fluid before replacing the sensor?
Absolutely. Low fluid is a common cause of low pressure sensor readings and is much cheaper to fix than replacing a sensor.
Can a transmission cooler leak cause P0847?
Yes, a leak in the transmission cooler or its lines can gradually lower fluid level and reduce pressure, triggering a low pressure sensor code.
Is sensor B located in the same area as sensor A?
They are typically both on the transmission case or valve body, but at different locations monitoring different circuits. Refer to your vehicle service manual for exact locations.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose P0847?
-
Check transmission fluid level first
-
Measure voltage at pressure sensor B connector
-
Test for a short to ground in the signal wire
-
Replace sensor B if wiring and fluid level are verified good
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)
Which Vehicles Commonly Get P0847?
- 2007-2017 Nissan Maxima (CVT)
- 2010-2020 Subaru Forester (CVT)
- 2008-2018 Honda Accord
- 2009-2019 Toyota Camry
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