Powertrain, generic (extended)

P23FC Cylinder 11 Injector B Air-Fuel Ratio Imbalance

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

P23FC is reserved for cylinder 11, so it can only belong to twelve-cylinder engines that add an extra injector in every cylinder. Such a pairing is hard to find in public engine data. Volkswagen's W12 illustrates the point: its early versions used twelve injectors in the intake manifold, one per cylinder, while the 6.3 FSI of the Audi A8 L W12 switched to direct injection with six-hole high-pressure injectors, again one per cylinder. Neither layout has an injector B. Any twelve-cylinder engine built with dual injection would still fall under CARB's imbalance rule, including the expectation that the code names the cylinder to the extent the detection strategy permits. No manufacturer documents P23FC. Should it appear, compare P21A6, P0311 and the circuit code P21D9 before replacing anything.

Likely causes

Second injector of cylinder 11 delivering a wrong quantity

Intake leak at cylinder 11

Code read from an engine that has no injector B (scan tool or software issue)

Symptoms

Check engine light on
Hardly any change in smoothness on a twelve-cylinder engine

Repair estimate

DifficultyShop_onlyWorkshop job

Parts and labour€200–1,800

Time2–10 h

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

Parts involved

fuel injector b cyl 11

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