Powertrain, generic (extended)

P23FB Cylinder 10 Injector B Air-Fuel Ratio Imbalance

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

P23FB marks cylinder 10, the highest cylinder number of a V10. Among dual-injection engines, the Huracán's 5.2 litre unit is the documented case; it adds multi-point injection to direct injection. In its firing order cylinder 10 follows directly after cylinder 5. On a ten-cylinder engine an injector B deviation in cylinder 10 shows up mainly in the bank that includes cylinders 6 to 10, which is why a bank code (P219B) or a misfire code (P0310) may be the only entry. CARB requires imbalance detection for such cars too, and since 2019 to 2021 also tracking of how frequently the check runs to completion in everyday use. No manufacturer documents P23FB publicly. P21A5 and the circuit code P21D8 are the companion codes.

Likely causes

Port injector of cylinder 10 dirty or worn

Injector seal leaking air at cylinder 10

Heat-damaged wiring to injector B of cylinder 10 (check P21D8)

Symptoms

Check engine light on
Bank 2 or misfire code stored alongside
Mostly no noticeable change

Repair estimate

DifficultyShop_onlyWorkshop job

Parts and labour€200–1,500

Time2–8 h

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

Parts involved

fuel injector b cyl 10

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