P0091 - FUEL PRESSURE REGULATOR 1 CONTROL CIRCUIT LOW

DTC code P0091 OBD2 means that the PCM has found a low-voltage signal from the control circuit of the fuel pressure regulator 1.

The regulator is usually controlled by the PCM. The regulator has a servomotor that places the regulating valve in the correct position so that the expected fuel pressure level is obtained according to the circumstance.

If the actual voltage of the regulator circuit is lower than the expected level, which is calculated by the PCM, this code is stored and the Check Engine light is illuminated.

• MIL (Engine Malfunction) light on.
• Delay in starting the engine.
• Large amount of black smoke exits the exhaust.
• Low fuel efficiency.

The diagnostic code P0091 OBDII is set when:

• The cables or connectors in the fuel pressure regulator circuit may be defective, causing a short circuit.
• The Fuel Rail Pressure may be defective.
• Fuel Rail Pressure (FRP) Sensor may be in poor condition.

To solve the problems caused by the fault code P0091 OBD2 you must do the following:

• You should inspect the system cables and connectors. If you find defects in these components you should repair or replace.
• Check the battery voltage level and ground at the fuel pressure regulator. If no voltage is present, you should check the status of the relays and fuses. You must also ensure a good ground fit.
• Change the Fuel Rail Pressure.
• Replace the Fuel Rail Pressure Sensor (FRP).