P2152: Why injector group C supply diagnosis is not a flow test

The documented P2152 monitor observes the high-side circuit described by GM as cylinder 3 injector “C.” The generic title instead emphasizes injector group C supply voltage circuit/open. Reading the actual monitor prevents the title from being mistaken for a complete diagnosis.

Electrical evidence depends on the command

The row contains two possible short-circuit observations. The output can remain low when the driver is off, indicating a ground-short pattern, or remain high when the driver is on, indicating a supply-short pattern. The stated maturation is two events, with other controller eligibility conditions referenced separately.

Those alternatives explain why neither a standalone voltage value nor the word “open” can identify the failed path by itself. The electrical observation needs its command-state context.

Keep fuel-system symptoms in their proper role

Poor combustion or reduced fuel delivery, if present, would be additional observations. This monitor does not measure the amount of fuel that the injector delivered and cannot establish a restricted nozzle from its electrical result.

A useful next step is to identify the exact driver channel and high-side wiring for the vehicle, then retain which of the two electrical conditions was reported. A generic group letter does not define all shared connections or their physical locations. The summary supports separating supply-side control faults from hydraulic performance problems; it does not provide a component-swap test, a pinout or evidence that the injector itself is necessarily defective.

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 711.