Powertrain, generic (extended)

P23F4 Cylinder 3 Injector B Air-Fuel Ratio Imbalance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P23F4 refers to cylinder 3: the control unit has found that this cylinder burns leaner or richer than the others and traces the deviation to injector B. On a three-cylinder engine with port and direct injection, such as the Ford 1.5 EcoBoost, cylinder 3 is the last one; on four- and six-cylinder engines it lies in the middle of the block or bank. CARB lets a manufacturer store a misfire code instead of an imbalance code if exact identification would need extra hardware and misfire detection catches the fault reliably. A P0303 can therefore stand for the same cause. No maker documents P23F4 publicly. Port injectors that drip or clog and a leaking seal at the intake port of cylinder 3 should be checked first; P219E is the matching code without the injector letter.

Likely causes

Port injector (injector B) of cylinder 3 dripping or partly blocked
Leaking seal at the intake port of cylinder 3
Low compression or leaking valves on cylinder 3

Symptoms

  • Check engine light on
  • Possible misfire code P0303 at the same time
  • Uneven idle when the engine is warm

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 3

Related codes

P219EP21D1P0303P23F3P23F5P23FE

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