[Dancake]

The fuel pressure regulator is bolted to the high pressure pump and has an electrical plug on it. They can be tricky to diagnose, but if they aren't working correctly they will cause fuel pressure deviations resulting in running issues. FPR's can fail in two ways. Either they won't allow enough fuel to cope with the need or demand, or they will allow excessive fuel to pass to the rail. Either way can cause running issues, including misfires and cutting out.

The cutting out symptom is normally as a result of a low pressure condition caused by a stuck or partially blocked FPR (when the FPR is the faulty component). You can unplug the FPR to see if the engine behaves any differently, but don't let it run for too long if it sounds like a machine gun. Of course the fault could also lie within the pump itself, but the FPR is quicker to check than the pump. You could try removing the FPR and cleaning it in something like an ultrasonic bath using a sensitive metals cleaning solution, or swap one out from a known working engine to see if it cures it.

Codes 2505 and 2503 don't necessarily indicate that your fuel pressure sensor is damaged. The codes have been stored because the fuel pressure has dropped below the parameters expected at a specific engine operating condition, perhaps at the point the engine cuts out. These codes sound like symptoms of another problem and not the cause. I'd try the FPR on the pump first and go from there. Volvo call it a fuel control valve for reference.