Diagnostic article Generic OBD-II
P2B0C: Cylinder 5 pulse monitoring depends on feedback being ready
Learn what P2B0C establishes during catalyst warm-up and why an unready feedback channel cannot be read as a passed injector test.
Read before applying this article
Documented application
2025 GM 25OBDG06A documented monitor only. Vehicle, engine and calibration applicability must be confirmed from the matching service information; no model fitment is inferred.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P2B0C addresses cylinder 5 injection-pulse performance during the catalyst warm-up period. The GM monitor looks for coil-voltage behavior associated with injector armature movement. It distinguishes the electrical command to inject from evidence that the commanded opening actually occurred.
Readiness is part of the diagnostic opportunity
The source requires small-pulse diagnostic enablement, catalyst warm-up enabled and fuel-pulse voltage-feedback data ready. If warm-up has ended or feedback data is not ready, an absent new fault cannot be interpreted as proof that this monitor completed successfully.
The check samples cylinder events rather than using a generic fixed-delay continuity test. Its published monitoring span is 50–100 samples. Two-trip reporting is separate from that event-level evaluation and does not define how quickly an individual injector should open.
Keep the converted opening metric in its calibration
The supporting material describes an opening-magnitude threshold and multipulse operating limits. Those are controller interpretation data; they are not an instruction to apply a listed value directly at an injector connector. The relevant fuel-pressure and pulse-mode context must remain associated with the feedback.
Record the cylinder-specific result, command opportunity and readiness state together. This code does not directly measure combustion contribution or prove a fuel-volume error. The source supports an investigation of missing opening evidence, while the applicable vehicle procedure is still needed to establish the electrical or mechanical cause.
Source and applicability
2025 GM 25OBDG06A documented monitor only. Vehicle, engine and calibration applicability must be confirmed from the matching service information; no model fitment is inferred. These criteria explain controller logic, not a complete repair procedure. 25OBDG06A, PDF page 562. 25OBDG06A, PDF page 823. 25OBDG06A, PDF page 824.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Cold Start Cylinder 5 Injection Pulse Performance
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT