Pressure Control Solenoid C Stuck On
The transmission's pressure control solenoid C is stuck in the open position, constantly allowing fluid to flow when it should be closed. Think of it like a faucet that won't turn off—fluid keeps flowing even when the transmission doesn't need it.
The ECM monitors solenoid C's electrical resistance and current draw during operation. It expects the solenoid to cycle on and off to modulate transmission pressure. A stuck-on condition shows continuous low resistance and sustained current flow that doesn't match shift commands.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Solenoid C Current | Cycles 0-600mA based on shift logic | Continuous current above threshold or no response to commands |
| Line Pressure Response | Pressure drops when solenoid commands off | Pressure remains high despite off commands |
Code P0797 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0797 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.