P0357: Coil G continuity is monitored with its driver switched off

P0357 addresses the primary control circuit of ignition coil G. In the GM monitor, an open-load diagnosis is made from low driver feedback while the output is switched off. Coil firing performance and electrical continuity are therefore separate questions.

Why the running conditions matter

Ignition must be synchronized, engine speed must exceed 1,400 rpm, and the ignition counter must advance by more than nine counts. The source explains that this counter condition ensures all cylinders have fired at least once.

The check uses a 0.4-second interval and two-trip reporting. A stationary-engine voltage reading cannot replace the qualified off-state observation, because it lacks that ignition history and control context.

Trace the electrical fault rather than assume a weak spark

Preserve the coil G driver status and the conditions when its open-load result occurred. A misfire may motivate investigation, but this particular row evaluates the primary electrical path; it does not measure spark energy at a plug.

The table prints an atypical upper battery-voltage limit, which is not adopted here as a usable service boundary. Confirm supply conditions and physical coil mapping in the appropriate vehicle information. The summary does not distinguish an interrupted load, connector, harness or driver by itself. Use the prescribed circuit procedure to localize the issue before selecting a replacement coil or controller.

Source and applicability

This explanation covers the cited GM monitor, not every vehicle carrying this code. The application-matrix filename does not resolve cleanly to this file, so no model or engine fitment is assigned. GM diagnostic table, PDF page 702; GM diagnostic table, PDF page 703.