P2309: A coil low-circuit fault with an unresolved channel label

The generic P2309 description names ignition coil D's primary low circuit. The cited GM table instead labels its P2309 row “Ignition Coil C.” That difference remains unresolved here; neither label is used to tell the reader which physical coil to remove.

The supported electrical failure pattern

The row describes the low-side driver circuit being low while the driver is off, interpreted as a short-to-ground condition. It lists a 0.4-second failure period, ignition synchronization and engine speed above 1,400 rpm among the operating conditions.

It also uses an ignition-event counter to ensure firing events have occurred before evaluation. Thus, an engine-off resistance observation or a brief idle-only check does not reproduce all the conditions described by this particular monitor.

Channel mapping must precede component work

The original PDF confirms that the conflicting coil letter is present in the source, rather than being introduced by text extraction. The same table contains an implausibly high upper battery-voltage entry, so that value is not offered as a workshop operating specification.

The useful conclusion is an off-state electrical fault in the applicable coil control channel. Establish that channel from the exact vehicle and calibration information before testing. A low primary-circuit diagnosis does not directly prove a failed spark plug, secondary insulation problem or mechanical misfire cause. Preserving command state, electrical fault status and event eligibility provides stronger evidence than replacing a coil based on the unverified letter alone.

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 699 · GM PDF, physical page 700.