P2151: Injector 2 high-side output is high during its off state

P2151 identifies a short-to-power signature in the injector 2 high-side circuit in the reviewed GM monitor. The generic code description uses group B supply voltage high. Circuit identification must follow the applicable vehicle information rather than assuming that the group letter provides universal cylinder numbering.

The monitor expects an off-state response

The controller compares driver voltage with its accepted range when the output is powered off. Its short-to-power design specification is a signal no more than one volt away from controller power. The finding is electrical persistence during an off command, not merely a high reading at some point in an injection event.

This distinction changes the useful recording: a voltage trace without command-state context cannot show whether the monitored condition was actually present. Similarly, a combustion symptom does not establish which part of this electrical circuit failed.

When a recorded event can recur

Battery voltage must be at least 11 V, and the listed P062B failure states must not be active. Ten failing observations out of 20 at 100-millisecond intervals meet the documented decision rule. Brief or intermittent behavior can therefore be relevant even if a later static check looks normal.

Use the vehicle-specific injector electrical procedure to separate wiring, load and driver evidence. Following an identified repair, confirm a valid off-state response and monitor completion under appropriate conditions. P2151 does not prove fuel leakage, identify a connector location or authorize a particular injector or controller replacement.

Source and applicability

The thresholds and component mapping apply only to the documented monitor, pending vehicle and calibration confirmation. GM diagnostic table, PDF page 606.