P21E4: Keeping a cylinder 5 injector low-circuit report tied to verified evidence

P21E4's generic label is cylinder 5 injector B circuit low. GM's evidence row belongs to injector channel 7. The document does not supply the channel-to-cylinder map, so the electrical explanation here must not be read as a location instruction for physical injector five or seven.

The diagnostic class and stage state

The source describes a short-to-ground category and evaluates output voltage above 5 V while the power stage is inactive. Those are controller diagnostic quantities; the summary does not identify a corresponding external probing point.

The row uses three events for maturation and requires suitable engine speed and supply conditions. Its adjacent channel entries separate an open-load voltage window from an active-stage high-current failure. Keeping those categories distinct is more useful than collapsing them into a broad injector-performance problem.

How the limitation changes the next decision

The exact controller calibration and vehicle circuit information are needed before continuity or short-circuit tests can target the correct channel. A normal result on an assumed injector would not invalidate the monitor if that assumption selected the wrong path.

Record the original electrical category and power-stage state along with the code. This monitor does not measure spray, fuel quantity or combustion quality, and it cannot identify the injector as the failed component without additional circuit evidence. Verification should demonstrate a completed eligible electrical check, not just an empty fault memory after clearing.

Source and scope

2025 GM 25OBDG07A Part 2 monitor tables only; model, engine and transmission applicability are not established by the unresolved application-matrix filename join. These are documented monitor criteria, not a universal repair procedure. GM PDF, physical page 558.