P21D5: A cylinder 7 injector B open-load diagnosis with a separate document channel

P21D5 is generically associated with cylinder 7 injector B circuit/open. The GM row used as evidence is labeled injector 5. This article does not assume that the document channel number directly equals the engine's physical cylinder number.

What the source says about the failure

The electrical test checks output voltage from 3 V inclusive to below 5 V with the power stage inactive. Three events are listed for maturation. The table also requires engine speed of at least 80 rpm, a suitable supply-voltage window and the absence of relevant inhibiting conditions.

These details distinguish open-load recognition from an active-stage overcurrent failure. They are internal monitor criteria and do not prescribe an external test-pin voltage for an unverified injector location.

Identify the circuit before interpreting continuity

The unresolved mapping is consequential: a continuity test on the wrong physical channel could appear normal while leaving the reported fault unexplained. Exact controller, calibration and engine information should be retained when selecting the applicable circuit diagram.

Once identity is established, the open-load category helps direct the electrical investigation. It does not identify whether a connection, injector load or controller output caused that category, and it does not measure fuel delivery. Avoid equating a mechanical symptom with this specific electrical finding. A meaningful verification requires the same diagnostic class to complete under eligible conditions, rather than relying solely on a cleared fault memory.

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 557.