Powertrain, generic (extended)

P2B1C Cylinder 7 Injection Pulse Offset Not Learned

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2B1C says no learned offset exists for injector 7, which only applies to engines with at least seven cylinders, in practice V8s. No manufacturer publishes a monitor for this code. A GM patent on small-quantity adaption shows that a learn can also fail to finish because results do not settle: several test injections during fuel cut-off are compared, and an injector whose consecutive values scatter too much gets a low confidence rating and is marked suspicious instead of passing. A noisy speed signal, an injector with erratic opening or a leak in the high-pressure system can therefore block a valid value. Bosch's zero-fuel calibration patent rests on the same speed-based detection. CARB (f)(4.2.4)(A)(i) asks for missing learning to be flagged; P2B1D is the out-of-range sibling.

Likely causes

Test results for injector 7 scattering too much to be accepted
Learn restarted after injector or control unit replacement
Leak in the high-pressure system disturbing the test injection

Symptoms

  • Warning lamp
  • With an erratic injector, uneven idle or knocking on one cylinder

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 7engine control module

Related codes

P2B1DP2B1AP2B1EP02D8P02D9P0281

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