P2B12 code meaning
Cylinder 2 Injection Pulse Offset Not Learned
Powertrain system Generic code P2Bxx codes Check engine light
What P2B12 means
P2B12 is stored when injector 2's pulse offset has not been learned, so the controller still relies on a default value for the smallest injections. The public record contains no manufacturer using this exact code; the explanation here follows from the title and from the neighbouring monitors. Learning of this kind needs repeated coasting phases with fuel cut-off, because only then can the effect of a single test injection be picked up through the crankshaft speed signal, as a Bosch patent on zero-fuel quantity calibration sets out. Engines that rarely coast – long motorway runs, towing – or a recent adaption reset after injector work can therefore leave the learn unfinished. CARB treats feedback that never starts in time as a fault. Once learned but too far off, cylinder 2 reports P2B13 instead.
P2B12 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.3 to 5 hours
- Clears after repairAfter a drive cycle
Symptoms of P2B12
- Warning lamp without a clear driveability complaint
- Possibly louder combustion on cylinder 2 at low load
Common causes of P2B12
- Most likelyDriving profile without enough fuel cut-off phases (constant load, towing)
- PossibleAdaption values reset after work on injector 2 or the fuel system
- Less likelyCrankshaft speed signal too noisy to detect the test injection
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel injector cylinder 2Engine control module
What each part of P2B12 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| B | Area: hybrid propulsion. |
| 12 | The exact fault in that area. |
What to do next
- Note P2B12 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 P2B12
What does P2B12 mean?
P2B12 means "Cylinder 2 Injection Pulse Offset Not Learned". P2B12 is stored when injector 2's pulse offset has not been learned, so the controller still relies on a default value for the smallest injections. It is a generic code, so it means the same on every make.
Is it safe to drive with P2B12?
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 P2B12 fail an emissions test?
Yes, it can. P2B12 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 P2B12 to fix?
Difficulty: medium. A typical repair takes 0.3 to 5 hours of work. This is a job for a workshop.
Will P2B12 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.