The P0091 code on your 2023 Dodge Ram indicates an open circuit condition in the fuel pressure regulator control circuit. An open circuit means electrical continuity is broken somewhere in the system, preventing proper regulator operation.
Ram Engine Options
The 2023 Ram lineup includes the 3.6L Pentastar V6, 5.7L HEMI V8, 6.4L HEMI V8, and 6.7L Cummins turbo-diesel. Each engine has specific fuel pressure regulation requirements. The open circuit code applies to the electronic pressure control solenoid in the fuel system.
What Open Circuit Means
An open circuit indicates a break in the electrical path—the PCM can't communicate with the fuel pressure regulator solenoid. This typically results from a disconnected connector, broken wire, or failed solenoid coil that has opened internally. Without control signals, fuel pressure regulation is compromised.
Diagnostic Process
Locate the fuel pressure regulator solenoid for your specific engine. Check that the connector is fully seated. Measure solenoid coil resistance—infinite reading indicates an open coil. Test wiring continuity from the connector back to the PCM. Look for damaged wires, especially near heat sources.
Repair Solutions
A failed-open solenoid requires replacement. If wiring is damaged, locate and repair the break. Ensure all connections are secure after repair. Clear codes and verify proper pressure control through scan tool monitoring. The specific repair varies by engine type—diesel and gas systems differ.