P21E5: An active injector-current fault with an unresolved channel identity

P21E5 identifies cylinder 5 injector B circuit high in the generic catalog. The GM monitor table places it in the injector-7 channel group. The cited material does not map that internal channel to physical cylinder numbering, so the electrical explanation remains separate from a location instruction.

What makes the high-circuit result specific

The source evaluates output current above 3.8 A with the power stage active and describes the category as a short to supply. Three events are specified, subject to minimum engine speed, battery supply and referenced inhibition conditions.

The same channel has different voltage-based checks for an open load and a low-circuit condition while inactive. P21E5 therefore indicates a particular operating-state failure, not merely that any injector-related test was unsuccessful.

What evidence should accompany the code

Preserve activation state, reported driver category and controller calibration. These establish both what the monitor observed and which vehicle documentation is needed to identify the actual circuit.

The current threshold does not specify a permissible external test current or justify manually powering an injector. Nor does it establish a fuel-flow or spray defect. Even after the channel mapping is resolved, wiring, electrical load and power-stage causes require separate circuit evidence. A later zero current with the stage off cannot invalidate the earlier energized failure; recovery needs a completed eligible monitor result, not only a cleared code.

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.