Powertrain, generic (extended)

P21FA Fuel Control System B Too Lean at Idle (Bank 2)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P21FA is the bank 2 version of the idle lean check for the second fuel path. It applies to engines with two cylinder banks, a front oxygen sensor per bank and dual injection, such as Ford's 5.0 V8, which has combined port and direct injection since 2018. No manufacturer publishes this code; Ford monitors its port system per bank without separate idle cells and would store the fault as P2BF2. At idle the per-bank correction reacts strongly to small absolute errors, so a leak at bank 2's intake runners or gasket, or a partly blocked port injector on that side, are the first suspects while bank 1 stays clean. Drivers may notice an uneven idle or nothing beyond the warning lamp. The system A equivalent is P2189.

Likely causes

Intake leak at bank 2 runners or gasket
Partly blocked port injector on bank 2
Bank 2 front oxygen sensor reading lean

Symptoms

  • Check engine lamp on
  • Uneven idle

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–800
Time0.5–3.5 h

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

Parts involved

fuel injectorintake manifold

Related codes

P21FBP21F8P21F6P21FEP2189P2BF2

References: fordservicecontent.com, en.wikipedia.org, law.cornell.edu.