P2155: Interpreting injector group D’s high-side circuit fault across the source pages

P2155 is presented as injector group D supply voltage circuit/open in the generic catalog. GM's illustrated row describes cylinder 4 injector “D” and diagnoses shorts affecting the driver's high side. Its two alternatives extend across a page boundary.

Read both halves of the electrical test

On the first page, low voltage while the driver is off identifies a ground-short pattern. The continuation adds high voltage while the driver is on as the supply-short alternative. Omitting that continuation would incorrectly reduce the monitor to only one possible electrical direction.

The table lists two diagnostic events and references the controller's additional enable and inhibition rules. The code therefore does not identify an arbitrary two-second failure duration or guarantee that the test runs in every operating state.

What the group label leaves unresolved

The described cylinder/channel identity applies to the source's implementation. The generic letter alone does not establish which physical injectors share a power path in another engine, and the “open” title does not prove an interrupted conductor was the observed fault.

Preserve the actual driver fault category and command state. These distinguish a high-side electrical problem from an injector flow issue, which this monitor does not measure. The proper vehicle circuit information is required to locate the cause among wiring, load and control electronics. No direct injector energization or fuel-system disassembly procedure follows from this summary.

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 · GM PDF, physical page 712.