Line Pressure Relief Valve
WARNING: This page is about a different car, the 2004 Ford RV Cutaway, 2004 Ford Econoline, 2004 Ford E450 Super Duty, and 2004 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
The solenoid body assembly contains an over-pressurization relief valve that will limit the line pressure through the (PC-A) solenoid and feedback to the pump main regulator valve. The LPC relief valve controls line pressure spikes when cold. If this valve fails you may see concerns with the filter found in the solenoid body assembly.