P23FACylinder 9 Injector B Air-Fuel Ratio Imbalance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P23FA concerns cylinder 9, which among passenger-car engines fitted with dual injection realistically means a V10. The best-known example is the 5.2 litre V10 of the Lamborghini Huracán, described as the first V10 to combine direct and multi-point injection. Its firing order 1-6-5-10-2-7-3-8-4-9 alternates between cylinders 1 to 5 and 6 to 10, so cylinder 9 belongs to the second group and fires last. Five cylinders feed each exhaust sensor here, so the share of one faulty cylinder in the measured signal is small; CARB therefore permits a bank-wide or misfire entry if the method cannot isolate the cylinder. No manufacturer publishes P23FA, and NHTSA's bulletin index holds no entry for it. Check P21A4, P0309 and the circuit code P21D7.
- What you may notice
- Check engine light on
- Little or no effect on the high-revving engine's behaviour
- Bank trim of the second cylinder group shifted
- Likely causes
- LikelyMulti-point (port) injector of cylinder 9 deviating
- PossibleLeak in the intake path of cylinder 9
- RareValve seat or compression problem on cylinder 9
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €200 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.