Powertrain, generic (extended)

P23F3 Cylinder 2 Injector B Air-Fuel Ratio Imbalance

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

P23F3 points to cylinder 2 and to its injector B, the second of two injectors feeding that cylinder. The smallest engines able to raise it have three cylinders, for example Ford's 1.5 EcoBoost, which pairs port and direct injection and can switch one cylinder off at light load. On V engines the bank that holds cylinder 2 depends on how the maker numbers its cylinders, so read the service information before working on a side. Hyundai's Smartstream 1.0 and 1.2 MPi engines show that both injectors of a cylinder may also sit in the intake port; whether such a design calls one of them B is not published. No public document ties P23F3 to a vehicle. Compare with P219D for the same cylinder and with P21D0 for the injector B circuit.

Likely causes

Injector B of cylinder 2 delivering too much or too little fuel

Air leak at the intake port or injector seal of cylinder 2

Work done on the wrong cylinder because of the maker's numbering scheme

Chafed wire to injector B of cylinder 2 (check P21D0)

Symptoms

Check engine light on
Shaking at idle, most noticeable on small three- or four-cylinder engines
Slightly higher fuel consumption

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€80–800

Time0.5–4 h

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

Parts involved

fuel injector b cyl 2

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