P2B12Cylinder 2 Injection Pulse Offset Not Learned
- 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
- 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.
- What you may notice
- Warning lamp without a clear driveability complaint
- Possibly louder combustion on cylinder 2 at low load
- Likely causes
- LikelyDriving profile without enough fuel cut-off phases (constant load, towing)
- PossibleAdaption values reset after work on injector 2 or the fuel system
- RareCrankshaft speed signal too noisy to detect the test injection
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €0 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.