P0874 Transmission Fluid Pressure Sensor/Switch C Circuit Intermittent

P0874 points to an intermittent transmission fluid pressure sensor or switch C circuit fault. The C pressure signal is unstable only under certain conditions.

Code details

Generic OBD-II · P0

System: Transmission
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace hydraulic parts until the intermittent pressure sensor C circuit has been stressed and tested.

Symptoms of P0874

Harsh, delayed, or slipping shifts, or being stuck in one gear.
Check-engine light, sometimes with limp-home mode.
Flaring RPM or a shudder under load.

Common causes of P0874

Low or degraded transmission fluid.
A failing speed sensor, shift solenoid, or pressure-control circuit.
Wiring, connector, or internal hydraulic/mechanical faults.

Useful checks before replacing parts

Graph pressure sensor C data while repeating freeze-frame load, temperature, and shift conditions to catch dropouts or spikes.
Inspect pressure sensor C connector, internal harness, case connector terminals, shared reference, ground, and fluid intrusion.
Compare sensor C behavior with pressure-control commands, shift timing, slip, and companion pressure sensor codes.

Related OBD-II codes

These nearby transmission entries can help compare wording and pin down the fault area.