P0300 Random or multiple cylinder misfire detected
System
Powertrain - engine and transmission
What P0300 means
"Random or multiple cylinder misfire detected" is a count, not a diagnosis. The computer watches each firing of each cylinder and records the ones that did not produce the power they should have; this code is the one it files when those events are spread across more than one cylinder, or across no particular cylinder at all. The codes P0301 to P0312 are the same count filed against a single cylinder instead.
This is a standard code. It means the same thing on every make of vehicle.
What the program shows for P0300
The Misfire cyl cards on the Dashboard hold one live counter per cylinder, and the Full scan lists each cylinder's count for the last ten drives and for this drive with its share of the total, which is what tells a spread-out count from one cylinder's. A recorded drive gets a misfire rate worked out over that recording, and the Inspection screen says whether the misfire monitor has finished.
The Dashboard's Misfire count cards show one counter per cylinder once the engine is running, next to the Engine speed and Ignition timing traces. The Full scan's On-board self-tests give each cylinder's misfire count for the last ten drives and this drive with its share of the total, and a recorded drive works out a misfire rate over that recording for the Analysis screen and the printed report. The Inspection screen shows whether the Misfire detection monitor is done or still running.