Possible causes

– Faulty fuel pressure regulator
– Fuel pressure regulator harness is open or shorted
– Fuel pressure regulator electrical circuit poor connection
– Faulty fuel pressure sensor

When is the code detected?

Fuel rail pressure greater than 1450psi over desired rate

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P0089 ISUZU Description

The Engine Control Module (ECM) uses commanded fuel pump flow to determine a desired fuel rail pressure. The actual fuel pressure is monitored using the Fuel Rail Pressure (FRP) Sensor.