Transmission Fluid Pressure Sensor/Switch B Circuit Low
What does P0847 mean?
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.
Common Symptoms
- Check Engine Light illuminated
- Transmission slipping or flaring between gears
- Soft or delayed shifts
- Possible limp mode activation
Probable Causes (Ranked by Likelihood)
- 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
Step-by-Step Diagnostic Procedure
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Check transmission fluid level first
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Measure voltage at pressure sensor B connector
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Test for a short to ground in the signal wire
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Replace sensor B if wiring and fluid level are verified good
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.