There may be an intermittent three- to five-second delay between when you turn the key and when the engine actually cranks. If the Check Engine Light illuminates, the brake switch should be inspected and the PCM may need updated software.
Car Problem Reports
Chrysler 300 Inspect brake switch and update PCM if you experience CEL during cranking
Chrysler 300 Problem
Exhaust & Emissions Affected: V6