P0091 - Fuel Pressure Regulator '1' Control Circuit Low
Fuel Pressure Regulators are used to control and regulate the fuel system pressure to ensure a steady and sufficient supply of fuel depending on the current engine load. The ECM will normally operate some form of electrical solenoid / motor to regulate the fuel pressure based on feedback provided by the fuel pressure sensor.
Fault Code Explained
The ECM has detected that the Fuel Pressure Regulator Control Circuit is below it’s minimum parameter or is below what is expected for the current operating conditions.
Due to the variety of systems and methods used for Fuel Pressure Control it is recommended to follow the manufacturers test plan for this fault code.
The following are some of the general tests that should be carried out
- Check for Short to earth on Fuel Pressure Regulator circuit
- Check supply Voltage for Fuel Pressure Regulator circuit
- Test operation of Fuel Pressure Regulator Solenoid / Motor