P21E9: High-circuit injector evidence without a guessed cylinder-to-channel conversion

P21E9 is cataloged as cylinder 7 injector B circuit high. GM's cited row names injector channel 5. This unresolved mapping prevents the source channel number from being used as a physical-cylinder instruction, but it does not erase the row's useful electrical distinctions.

The current is judged only with the stage active

The source describes a short-to-supply category and requires output current above 3.8 A during power-stage activation. It specifies three events and additional engine-speed, supply and inhibition requirements. The value belongs to this controller's monitor, not an arbitrary externally powered injector test.

Neighboring entries for the document channel evaluate open load and low-circuit behavior in the inactive state. A current measurement after shutdown therefore cannot establish that the earlier high-circuit condition has recovered.

Use calibration identity to select the correct path

Retain controller information, complete code status and the active-stage diagnostic category. Vehicle-specific documentation must settle how the channel corresponds to injector B and the physical cylinder before circuit testing or component decisions.

The monitor does not directly assess fuel delivery and cannot determine whether an electrical load, harness connection or internal driver is responsible. A broad injector replacement based on the generic number would skip both the unresolved mapping and cause isolation. Meaningful verification requires a completed eligible electrical check on the correctly identified channel, rather than relying only on cleared memory or an engine that currently runs.

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.