P23F8 code meaning
Cylinder 7 Injector B Air-Fuel Ratio Imbalance
Powertrain system Generic code P23xx codes Check engine light
What P23F8 means
P23F8 identifies cylinder 7 and its injector B, so it needs at least seven cylinders, in practice a V8 or V10. Three V8 families using a pair of injectors in every cylinder are on record: Ford's 5.0 Coyote, which gained direct injection on top of port injection for the 2018 Mustang GT and F-150; Toyota's 2UR-GSE with D-4S in Lexus F models and the LC 500; and the supercharged GM LT5 in the 2019 Corvette ZR1, whose port injectors are driven by a separate fuel injection control module and listed as injector B (circuit codes from P21CF, Type A). None of them publishes P23F8; GM and Ford judge imbalance per bank. To narrow cylinder 7 down, use P21A2, the misfire code P0307 and the circuit code P21D5.
P23F8 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyHard
- Typical labor1 to 6 hours
- Clears after repairAfter a drive cycle
Symptoms of P23F8
- Check engine light on
- Fuel trim of one bank off while the other bank is normal
- Rarely a perceptible misfire
Common causes of P23F8
- Most likelyPort injector of cylinder 7 clogged or leaking
- PossibleIntake leak at cylinder 7
- Less likelyFault in the separate injector B driver module, where fitted (e.g. GM LT5)
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 7
What each part of P23F8 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. |
| F8 | The exact fault in that area. |
What to do next
- Note P23F8 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 P23F8
What does P23F8 mean?
P23F8 means "Cylinder 7 Injector B Air-Fuel Ratio Imbalance". P23F8 identifies cylinder 7 and its injector B, so it needs at least seven cylinders, in practice a V8 or V10. It is a generic code, so it means the same on every make.
Is it safe to drive with P23F8?
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 P23F8 fail an emissions test?
Yes, it can. P23F8 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 P23F8 to fix?
Difficulty: hard. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P23F8 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.