P0351: Cylinder 1 ignition-control open feedback during the off state

P0351's broad dictionary name refers to ignition coil A's primary control circuit. The cited GM row identifies cylinder 1 ignition-control output and specifically checks for an open circuit. It evaluates the low-side driver's voltage feedback while the output is powered off.

What the electrical check establishes

The controller's internal limits are designed around an open-circuit specification above 30 kΩ between signal and controller ground. That is a driver diagnostic definition, not a universal coil-winding resistance specification or permission to measure an energized circuit.

The test requires the engine to be running and ignition voltage above 11 volts. It counts 50 failing observations out of 63 at a 100-millisecond interval and is Type A, one-trip. A key-on check with the engine stopped does not reproduce all of these stated conditions.

Separate control wiring from spark quality

The code identifies an abnormal control-path response. It does not independently establish plug condition, secondary spark strength or the exact component containing the opening. Confirm the vehicle's mapping between cylinder 1, its ignition unit and the controller output.

Preserve related supply and ignition codes before selecting a test. Follow the applicable electrical procedure, then verify the completed off-state driver monitor while the engine is running. A disappearance of misfire alone is useful but does not prove that this specific circuit diagnosis passed.

Source and applicability

This explanation is limited to the 2025 GM 25OBDG03A monitor on page 271. Its thresholds are calibration examples, not universal specifications. Confirm the vehicle, engine and controller procedure before applying them.