P23F4 code meaning
Cylinder 3 Injector B Air-Fuel Ratio Imbalance
Powertrain system Generic code P23xx codes Check engine light
What P23F4 means
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.
P23F4 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of P23F4
- Check engine light on
- Possible misfire code P0303 at the same time
- Uneven idle when the engine is warm
Common causes of P23F4
- Most likelyPort injector (injector B) of cylinder 3 dripping or partly blocked
- PossibleLeaking seal at the intake port of cylinder 3
- Less likelyLow compression or leaking valves on cylinder 3
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 3
What each part of P23F4 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. |
| F4 | The exact fault in that area. |
What to do next
- Note P23F4 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 P23F4
What does P23F4 mean?
P23F4 means "Cylinder 3 Injector B Air-Fuel Ratio Imbalance". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P23F4?
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 P23F4 fail an emissions test?
Yes, it can. P23F4 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 P23F4 to fix?
Difficulty: medium. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will P23F4 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.