P0274: why injector 5 can register a high control circuit

P0274 identifies an electrical condition on injector 5 in this GM monitor: the low-side driver remains high when it is commanded on. The documented interpretation is a short to the power supply, rather than a measurement of excessive fuel delivery.

Read the command state with the fault

The table associates the failure with a path of 0.5 ohm or less between the low-side pin and controller power. That is the monitor's fault characterization, not permission to measure resistance on an energized injection circuit. The important diagnostic distinction is that the voltage is abnormal during the on phase; a voltage reading without the commanded state loses that context.

When the result is meaningful

Monitoring requires battery voltage above 11 V, at least one second of engine operation, no cranking and an injection request. Four failed samples out of eight, sampled at 100 ms, constitute the listed failure filter. Consequently, a key-on observation without an injection command cannot reproduce the complete test.

Preserve the operating conditions and have the cylinder-5 circuit identified from vehicle-specific service information. Confirmation should establish whether its electrical response matches the command under enabled conditions. The code alone does not distinguish a harness fault from the connected electronics or prove that injector replacement will correct it.

Source and applicability

2025 GM 25OBDG04B diagnostic parameter tables; the cited monitor only. Vehicle, engine and calibration applicability must be confirmed separately. These tables describe detection logic, not a complete repair procedure or a component replacement verdict. gm-2025-04b, PDF page 1134.