The P0799 code indicates that the engine control module has detected an intermittent electrical or mechanical fault within the Pressure Control Solenoid C circuit. This solenoid is responsible for regulating the hydraulic pressure used to engage clutches or bands within the transmission.
The solenoid may have internal electrical failure or a sticking plunger that prevents consistent pressure regulation.
Debris or sludge in the fluid can cause the solenoid to stick or block hydraulic ports, leading to intermittent performance.
Frayed wires, corrosion in connectors, or loose pins can cause a fluctuating electrical signal to the solenoid.
Worn bores or leaking seals within the valve body can cause pressure loss, making the solenoid appear to be malfunctioning.
An internal fault in the PCM or TCM may cause incorrect signals to be sent to the solenoid, though this is the least common cause.
No, P0799 often points to an electrical or hydraulic control issue that can be resolved by replacing a solenoid or cleaning the valve body without a full rebuild.
While replacing the solenoid often works, it is critical to check for fluid contamination first, as debris can cause a new solenoid to fail quickly.
No. While some may suggest replacing the PCM, it is rarely the cause of P0799; the fault is almost always located in the solenoid itself or the wiring.