tn hillbilly

Went to start my truck last night, and it sounded like it had a major fuel knock. I checked the codes and it came up P0088. I took it into the stearlership this morning, and they said Cam Shaft Sensor and Fuel Pressure Sensor are bad. Ok no big deal, warranty is going to cover them. The Service Manager also said his tech wants to check to the injection system and change the fuel filter for metal shavings?? Which wouldn't be warrantied. I told him I would change my own filter. Is it possible to have metal shavings if just those 2 sensors went out?? Any help is much appreiciated.

Marshall