Transmission Fluid Pressure Sensor/Switch B Circuit Low
What it means
P0847 means the transmission fluid pressure sensor/switch 'B' is reporting an abnormally low voltage, so the module loses a reliable pressure reading. The engine still starts and the car drives, but you may notice slipping, rough shifts, or a protective limp mode. Typical causes are a failing pressure sensor, low or dirty fluid, or a wiring fault in its circuit.
Can I keep driving? Usually drivable, but the transmission may slip or shift roughly and can drop into limp mode; fix it before it strains the gearbox.
Real-world scan data
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check-engine light on
- Transmission slipping
- Rough or delayed shifting
- Possible limp mode (reduced gears)
Common causes
Most likely first
- Faulty transmission fluid pressure sensor/switch 'B'Likely
- Low or contaminated transmission fluidCommon
- Damaged wiring or a poor connector in the sensor circuitCommon
- Faulty transmission control module (TCM)Less often
How to diagnose & fix
Work through it in order
- Check transmission fluid level and condition first; correct if low or burnt.
- Inspect the sensor connector and wiring for a short-to-ground or open causing the low signal.
- Measure the sensor's signal voltage and compare to spec.
- Replace the transmission fluid pressure sensor/switch if it fails testing.
- Replace the TCM only after wiring and sensor causes are ruled out. Clear and road-test.
FAQ
Quick answers
Is it safe to drive with P0847?+
Can I just clear P0847?+
Related codes
Read & clear P0847 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.