P0FFFNot Documented - No Defined Meaning

How the car detects it: P0FFF has no documented meaning. CARB requires the SAE J2012-defined codes such as P0xxx and P2xxx wherever possible and allows manufacturer-defined codes only in the ranges J2012 sets aside for them, such as P1xxx. None of the public J2012 title lists checked for obdex assigns a code in the P0Fxx block, and no vehicle maker, regulator filing or bulletin in the NHTSA archive uses P0FFF. If a scan tool reports P0FFF, the likely causes are a reading error, a tool with a faulty code table or a maker-specific code shown with the wrong prefix; check the raw data and the manufacturer's own code list.

Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.