OBD-II code P0797 indicates that the Powertrain Control Module (PCM) has detected the pressure control solenoid C is stuck in the 'on' position. This solenoid regulates transmission fluid pressure for shift control; when stuck on, it can cause constant high pressure, leading to harsh shifts, slipping, or transmission damage.
Insufficient fluid level or degraded fluid can cause the solenoid to stick mechanically or hydraulically.
The solenoid itself may be mechanically stuck open due to internal wear, debris, or coil failure.
A restricted filter can starve the solenoid of proper fluid flow, leading to sticking or pressure anomalies.
Corrosion, broken wires, or loose connectors in the solenoid circuit can cause incorrect signals or intermittent operation.
A malfunctioning pressure sensor may send incorrect feedback to the PCM, falsely indicating a stuck solenoid.
Only after all other components and wiring are verified good should the PCM be suspected; internal driver failure is uncommon.
It is not recommended. Driving with a stuck pressure control solenoid can cause harsh shifts, slipping, and potentially severe transmission damage.
No, PCM failure is very rare for this code. The most common causes are low/dirty fluid, a faulty solenoid, or wiring issues. Always rule out these simpler causes first.
It means the solenoid is mechanically or hydraulically stuck in the open position, delivering constant pressure even when the PCM commands it off, disrupting normal shift control.
In some cases, fresh fluid and a new filter can free a solenoid that is stuck due to sludge or varnish. However, if the solenoid is mechanically failed, replacement is necessary.