P0870
Transmission Fluid Pressure Sensor/Switch C Circuit
Transmission / hydraulic control
Generic OBD-II
Medium
What it means
P0870 means the transmission control module sees a problem in the circuit for fluid pressure sensor/switch C. Correct hydraulic pressure controls how gears apply, so a faulty signal here can cause slipping, delayed shifts, and extra heat. The engine still starts and runs — this is a transmission pressure-circuit fault, not an engine problem.
Medium
Can I keep driving? Often drivable, but expect delayed or harsh shifts and possible slipping — repair soon to avoid overheating the transmission.
Common symptoms
What you'll notice
- Check-engine light on
- Delayed or harsh shifting
- Transmission slipping or shifting poorly
- Transmission may run hot or enter limp mode
Common causes
Most likely first
- Wiring or connector fault in the pressure sensor/switch C circuitLikely
- Loose or corroded electrical connectorsCommon
- Faulty transmission fluid pressure sensor/switch CCommon
- Failed transmission control module (rare)Less often
How to diagnose & fix
Work through it in order
- Check transmission fluid level and condition, then read freeze-frame data.
- Inspect the pressure sensor/switch C connector and wiring for damage, corrosion, or loose pins.
- Test the circuit for continuity and correct voltage with a multimeter.
- Replace the transmission fluid pressure sensor/switch C if it reads incorrectly with wiring confirmed good. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0870?+
Short trips are usually possible, but slipping and poor shifts can overheat and damage the transmission, so get it diagnosed soon.
Can I just clear P0870?+
It will clear, but returns once the pressure signal is out of range again until the sensor or wiring is repaired.
Related codes
Often seen with P0870
Read & clear P0870 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