P2146: The injector group A supply diagnosis includes short-circuit behavior

The generic P2146 label refers to injector group A supply voltage circuit/open. The cited GM row is more specific about its diagnostic mechanism: it describes the high-side driver for cylinder 1 injector “A” and checks for short-to-ground or short-to-supply behavior.

Two command states reveal different faults

A low voltage with the driver off is the documented ground-short pattern. A high voltage with the driver on is the alternative supply-short pattern. The source combines these possibilities under the same code and lists two diagnostic events for maturation.

This means the word “open” in a generic scanner title does not establish that the controller detected an open conductor in this implementation. The actual row and the available driver status are needed to determine which electrical behavior was seen.

Identify the circuit before judging fuel delivery

The document's cylinder and letter naming applies to this table, not automatically to every vehicle using P2146. Establish the exact calibration and wiring arrangement before assuming which injectors share a supply or which connector is involved.

The monitor tests electrical behavior on the high side of the driver. It does not directly measure injector flow, spray quality or rail-pressure performance. Preserve command-state information and companion circuit faults so that a supply-side event is not mistaken for evidence of a mechanically blocked injector. The summary supports an electrical investigation but supplies no justified replacement instruction or safe direct-energization procedure.

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.