P0090 - FUEL PRESSURE REGULATOR 1 CONTROL CIRCUIT OPEN
POST UPDATED IN September, 2020
Description of DTC code P0090 Generic
When the DTC code P0090 OBDII is stored, it is because the PCM (Powertrain Control Module) has observed an open circuit in the electronic fuel pressure regulator, this regulator is designated as 1 in systems that use multiple fuel pressure regulators. It should be noted that this designation does not refer exclusively to the engine bank.
The pressure regulator is controlled by the PCM. It has a battery voltage signal cable and a ground signal cable, which operate a servo motor that places a valve, which can reach a desired fuel pressure level in any circumstance. When a voltage is applied to the engine from the regulator, the valve opens in small increments, and the fuel pressure increases. At the moment the voltage is reduced, the servo motor retracts and a spring forces the valve to close, there the fuel pressure is reduced.
The Fuel Rail Pressure Sensor (FRP) lets the PCM to check fuel pressure and control the tension of the fuel pressure regulator as needed. Although the two components may be integrated into a single housing, they are separate.
The diagnostic code P0090 OBD2 is set because of the following reasons:
Fuel pressure regulator cables or connectors may be defective, thus shorting the circuit.
The fuel pressure regulator may be in bad condition.
The FRP sensor may be defective.
Possible solutions of the DTC code P0090 Generic
The steps to solve the problems of the P0090 OBDII error code are as follows:
Check the entire wiring system as well as the connectors that relate to the fuel pressure regulator. Note that these components are exposed to high temperatures because they are close to the engine. If you find problems with them, you must repair them. Then, clear the code.
If the code returns, check the voltage and ground of the regulator. If no voltage is present, test the power supply relays and fuses according to the wiring diagram. Also, you should use the diagram to know the location of the ground. You must make sure that all these circuits meet the manufacturer's specifications.
If the voltage and ground values are OK, test the system pressure using a fuel pressure gauge. Watch the fuel system data while the scanner displays the manual fuel pressure. If the fuel pressure reflected on the scanner data screen does not match the actual fuel pressure, the Fuel Rail Pressure Sensor is defective, replace it.
To check the condition of the fuel regulator, you should see if changes in actual fuel pressure occur with variations in fuel pressure voltage. If not, the problem is in the regulator circuit or in the regulator itself.