To keep the fuel pressure constant, the vehicles are equipped with a fuel pressure regulator.
There are vehicles that have a fuel pressure system that is integrated into the fuel rail assembly. There are also vehicles that have a fuel supply with no return. In the latter, the regulator is part of the fuel pump module inside the tank. It should be noted that, when the fuel supply is non-return, it is controlled by the PCM (Power Train Control Module), in addition, the fuel pump output and the fuel rail pressure is determined by the FRP sensor (Fuel Rail Pressure Sensor) who uses the fuel temperature to determine the fuel pressure.
When the DTC codeP0089 OBD II is set, it means that the PCM (Powertrain Control Module) has concluded that the fuel pressure is not within the specifications already predetermined by the manufacturer.
The factors that lead to the establishment of fault code P0089 OBD2 are:
Maybe the fuel filter is clogged.
Restricted fuel lines.
The fuel pump outlet is not within specifications.
The fuel pressure regulator may be defective.
Defective fuel pump.
Possible solutions of the DTC code P0089 Generic
Before the diagnostic code P0089 you must do the following:
Inspect the fuel lines. Verify that they are in good condition. If you get defects in one of them, repair it or change if necessary.
Check the fuel pressure regulator; this usually has a vacuum line, which mechanically restricts the fuel according to the amount of vacuum delivered by the engine. Make sure there are no defective or loose vacuum hoses. Repair if you find problems.
If the suction hose has fuel, the regulator may have an internal leak causing a loss of pressure. You could put a clamp that does not damage the hose. But if the fuel pressure is higher taking the restriction, the regulator can have damage, you must change it.