P23FA code meaning
Cylinder 9 Injector B Air-Fuel Ratio Imbalance
Powertrain system Generic code P23xx codes Check engine light
What P23FA means
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.
P23FA at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor2 to 8 hours
- Clears after repairAfter a drive cycle
Symptoms of P23FA
- Check engine light on
- Little or no effect on the high-revving engine's behaviour
- Bank trim of the second cylinder group shifted
Common causes of P23FA
- Most likelyMulti-point (port) injector of cylinder 9 deviating
- PossibleLeak in the intake path of cylinder 9
- Less likelyValve seat or compression problem on cylinder 9
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel injector b cyl 9
What each part of P23FA means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 3 | Area: ignition system or misfire. |
| FA | The exact fault in that area. |
What to do next
- Note P23FA and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P23FA
What does P23FA mean?
P23FA means "Cylinder 9 Injector B Air-Fuel Ratio Imbalance". P23FA concerns cylinder 9, which among passenger-car engines fitted with dual injection realistically means a V10. It is a generic code, so it means the same on every make.
Is it safe to drive with P23FA?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P23FA fail an emissions test?
Yes, it can. P23FA is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P23FA to fix?
Difficulty: workshop only. A typical repair takes 2 to 8 hours of work. This is a job for a workshop.
Will P23FA clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.