fuel pressure regulator
 

I recently bought my first diesel. 2001 chev with duramax. My check engine light comes on then goes off after some mileage then comes back on . I have a code reader and it says pressure regulator 1 performance. Truck has 137xxx miles and chevy replaced the injectors at about 135xxx about 500 miles before I bought it. Previous owner spared no expense and took meticulous care of this truck. I'm no dummy when it come to mechanics. But this is my first diesel. what do I need to do?
Thanks Herb