Pressure Control Solenoid "B" Open Circuit
The transmission's pressure control solenoid B has lost electrical connection, like a light switch that's been disconnected from the wall. Without this signal, the transmission can't properly regulate fluid pressure, causing shifting problems.
The ECM monitors the solenoid coil's resistance and current draw during operation. It expects a completed circuit with specific voltage and amperage when the solenoid is commanded on. An open circuit produces no current flow, triggering the fault code.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Solenoid Coil Resistance | 4-10 ohms (varies by design) | Infinite ohms (open circuit detected) |
| Solenoid Current Draw | 0.5-2.0 amps when energized | 0 amps or no response |
Code P1793 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, P1793 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.