P0796 indicates the transmission control system has detected that Pressure Control Solenoid C is not engaging properly, remaining in its default 'off' (de-energized) position. This solenoid controls line pressure in the automatic transmission, and when stuck off, it can cause improper gear engagement, harsh shifting, or slippage.
The solenoid itself has internal electrical failure, sticking mechanically in the off position, or its internal valve is stuck closed preventing pressure buildup.
Damaged, corroded, or loose wiring/connector to the solenoid can prevent proper signal or power delivery, causing the solenoid to remain in the off state.
Insufficient fluid pressure or varnish/contamination can prevent the solenoid from operating correctly and may cause mechanical binding.
The sensor that monitors line pressure may be providing incorrect data to the TCM, causing it to believe the solenoid is stuck when it is actually functioning.
The valve body passages that the solenoid controls may be clogged or worn, preventing proper pressure regulation even when the solenoid operates correctly.
Rarely, the TCM may have a software or hardware issue preventing it from commanding the solenoid properly; this is the least likely cause and should be diagnosed only after other causes are ruled out.
Almost never. The TCM itself is rarely the cause of P0796. In the vast majority of cases, the problem is the solenoid, wiring, fluid, or pressure sensor. Technicians who jump to PCM replacement often misdiagnose the issue; this should be the very last thing checked.
It is not recommended to drive far or aggressively. The vehicle may be stuck in neutral, fail to shift properly, or enter limp mode. Continued driving with a stuck pressure control solenoid can lead to internal transmission damage from low line pressure.
P0796 is less common than many transmission codes but does occur. It is seen more frequently in higher-mileage vehicles where the solenoid has worn or the transmission fluid has degraded.
Costs vary significantly by vehicle. Solenoid replacement typically ranges from $200-$600 in parts and labor, but can exceed $1000 on some vehicles requiring transmission removal. Fluid service or wiring repairs may cost less.