P0090 GMC -what causes this when the fp sensor is new?

Question

New PC3 and fuel pressure sensor less than 600 miles ago.

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Answer 1

P0090 Fuel pressure regulator 1 control circuit

What cause this code are open circuit especially Ignition 1 , The other that can set this code condition is the FPR (fuel pressure regulator) it self rather than a open circuit to the Fuel Pressure Regulator, which is now a servicable item apart form the fuel injection pump, GMC has produced a TSB for the Fuel pressure regulator which may apply to you code condition. TSB # 03-06-04-010.Titled Fuel System Diesel fuel pressure regulator replacement.Before replacing the FPR check the circuit to this at its supply voltage,