A method of verifying a cylinder deactivation mode on an engine is provided. The method can include activating an ignition device in a deactivated cylinder during an exhaust stroke of the deactivated cylinder. The method can include measuring a voltage of the ignition device. The method can include comparing at least one of an amplitude and a timing of a measured spike of the voltage against a baseline voltage spike. The method can include indicating a status of the deactivation mode based on the comparison against the baseline voltage spike.