P0090 code definition

A P0090 diagnostic trouble code is referencing an issue with the fuel pressure regulator circuit.

This code is similar to P0089, P0091, and P0092.

What the P0090 code means

P0090 is an OBD-II code telling us there is a fault found within the fuel pressure regulator control circuit. This DTC is triggered when the ECM finds out-of-range performance from the control circuit. Out of range performance causes a Check Engine Light and a failsafe mode. Failsafe mode will remain in effect until normal sensor operation is detected or the issue is fixed.

What causes the P0090 code?

The fuel pressure regulator code may have some common causes:

  • Open or short in wiring harness
  • Fuel pressure regulator that has failed
  • Engine control module that is faulty
  • Poor electrical connection in the fuel pressure regulator control circuit

What are the symptoms of the P0090 code?

Common symptoms are:

  • Poor running vehicle
  • Failsafe mode set
  • Check Engine Light illuminated on the dashboard
  • Fuel economy that is lower than normal

How does a mechanic diagnose the P0090 code?

The mechanic will begin by checking for any diagnostic trouble codes (DTC’s). DTC’s will have freeze frame data associated with each code that this tells us important information for the test drive.

Next, the code will be cleared and a road test is performed. The road test should be under similar conditions to the freeze frame data.

A visual inspection will be performed to look for any damaged or broken wiring, sources of poor connection, and proper operation of the fuel pressure sensor.

A scan tool will be used to monitor fuel pressure control system operation. If the fuel pressure regulator control solenoid operates properly, then a manufacturer specific ECM test must be performed.

Common mistakes when diagnosing the P0090 code

Mistakes are commonly made when steps are not followed in order or are skipped altogether. Though the fuel pressure regulator is the typical cause, it must be tested before it is condemned and replaced. This will prevent repairs from being performed that do not address the actual fault.

How serious is the P0090 code?

Most people may only notice the Check Engine Light and no other adverse symptoms. In cases where drivability concerns are present, the vehicle should be checked immediately by a qualified mechanic.

What repairs can fix the P0090 code?

Typical repairs for P0090 are:

  • Repair of an open or short in the wiring harness
  • ECU replacement if it fails test procedures
  • Replacement of the fuel pressure regulator
  • Fixing poor electrical connections

Additional comments for consideration regarding the P0090 code

Professional scan tools are standard equipment for qualified mechanics. These scan tools will be required to view live sensor data, changes over time, readings from the ECU, and fuel pressure. In contrast, standard scan tools will only show what codes are present and will not be able to provide as extensive data.

Need help with a P0090 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

This article originally appeared on YourMechanic.com as P0090 OBD-II Trouble Code: Fuel Pressure Regulator 1 Control Circuit and was authored by Spencer Clayton.


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