P0847
Transmission Fluid Pressure Sensor/Switch B Circuit Low
Transmission
Generic OBD-II
Medium
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.
Medium
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.
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?+
Brief driving is usually okay, but slipping or limp mode places extra load on the transmission. Have it looked at soon.
Can I just clear P0847?+
It returns until the fluid, wiring, or pressure sensor fault is repaired.
Related codes
Often seen with P0847
Read & clear P0847 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX