Powertrain, generic (extended)

P23F7 Cylinder 6 Injector B Air-Fuel Ratio Imbalance

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

P23F7 belongs to cylinder 6, the highest-numbered cylinder on a V6 or straight six. Toyota's GR V6 family is a typical carrier: the 2GR-FSE in the Lexus IS and GS and the later 2GR-FKS both use D-4S, in which the port injector supplies part of the fuel next to the direct injector, its share depending on load and engine speed. Ford's PFDI V6 engines follow the same idea. Because the split changes with the operating point, a faulty port injector may only show in the ranges where it delivers much of the fuel, which makes the fault hard to reproduce on a short test drive. CARB requires the imbalance check for these petrol engines, but no manufacturer documents P23F7 itself. Read P21A1, P0306 and the circuit code P21D4 for the same injector.

Likely causes

Port injector of cylinder 6 deviating in the ranges where it carries most of the fuel

Air leak at the intake runner or injector seat of cylinder 6

Injection split calibration needing a software update

Symptoms

Check engine light on
Fault comes and goes depending on driving style
Occasional roughness at low or medium load

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€100–900

Time1–5 h

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

Parts involved

fuel injector b cyl 6

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