Common Checks
- Compare commanded and actual fuel pressure on a scan tool.
- Inspect the fuel-rail pressure sensor connector and vacuum reference where equipped.
- Check fuel pump, filter, and wiring if pressure is low.
Diagnostic trouble code
P0191 Fuel Rail Pressure Sensor Range/Performance
The PCM sees fuel-rail pressure data outside the expected range for operating conditions.
Fuel Pressure & Delivery CodesCommon Repairs
- Repair fuel-rail pressure sensor wiring or replace a failed sensor.
- Repair weak fuel delivery if pressure testing confirms it.
- Address vacuum-reference hose issues on systems that use them.
Mustang Notes
- Returnless fuel systems rely heavily on scan-tool pressure data.
Model-Year Applicability
Listed for 1999 and newer traditional gasoline Mustang pages in this first-pass catalog. Engine, calibration, and Ford-specific codes may narrow that range as more service data is added.