Powertrain, generic (extended)

P2B12 Cylinder 2 Injection Pulse Offset Not Learned

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

Likely causes

Driving profile without enough fuel cut-off phases (constant load, towing)
Adaption values reset after work on injector 2 or the fuel system
Crankshaft speed signal too noisy to detect the test injection

Symptoms

  • Warning lamp without a clear driveability complaint
  • Possibly louder combustion on cylinder 2 at low load

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–1,500
Time0.3–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel injector cylinder 2engine control module

Related codes

P2B13P2B10P2B14P02CEP02CFP0266

References: law.cornell.edu, patents.google.com.