When the engine is started for the first time after parking the vehicle overnight in cold conditions (below 32 degrees Fahrenheit / 0 degrees Celsius), some vehicles may exhibit a rough idle and/or the check engine light on with any of the following DTC(s) stored in memory. P0300 - Random misfire detected P0301 - Cylinder No.1 misfire detected P0302 - Cylinder No.2 misfire detected P0303 - Cylinder No.3 misfire detected P0304 - Cylinder No.4 misfire detected. This may be caused by frozen water accumulated in the main silencer, restricting exhaust flow.