The use of the spark plug means compression ignition can be timed, and means with simple timing adjustments and by injecting a leaner or richer mixture, the transition between spark and compression ignition cycles can be constantly varied. (evo.co.uk)
For some codes, the light will re-set (turn off) by itself, although it might re-set only after a certain number of ignition cycles. (yourmechanic.com)
While the storage of this code also leads to the illumination of the Check Engine Light, some vehicle makes and models require multiple ignition cycle with such a failure taking place before the Check Engine Light illuminates. (yourmechanic.com)