Note 15
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2005 Ford RV Cutaway, 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Excursion. However, it is still accessible from the selected car via links, so may be relevant.
Carry out the KOEO self-test. Diagnose all other DTCs first. Clear the DTCs. Repeat the KOER self test. If DTC P1284 is retrieved again, refer to the PERFORMANCE DIAGNOSTIC PROCEDURES to diagnose the high pressure oil system.