P21FF Fuel Control System B Too Rich at Higher Load (Bank 2)

P21FF closes the series: bank 2's second fuel path is rich in the upper load range although its correction already removes the largest reduction allowed. No manufacturer publishes criteria for it. Under CARB, a fuel system fault must be stored once adaptive control has exhausted the range the maker allows; threshold, load window and the number of trips are left to the manufacturer. On a V engine with dual injection, port injectors on bank 2 that over-deliver at long pulse widths, or excessive pressure in the shared low-pressure rail, would push this bank rich. If only bank 2 is affected, also compare the bank 2 front sensor signal with bank 1. Drivers rarely feel anything, but consumption rises. P2194 is the system A twin, P21FD the bank 1 code.

Likely causes

Symptoms

• Check engine lamp on
• Increased fuel consumption

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, patents.google.com, fordservicecontent.com.