My 2003 CRV has had the CEL on for about a year, but now at idle it occasionally blinks on and off, then stays on when driving is resumed. The original code when the light first came on last year was a cylinder misfire. Any ideas why it blinks sometimes? Idle speed seems normal, although it has stalled a few times over the last couple months.

 

With the CEL flashing it should be in limp mode (won't go over a certain RPM so you don't hurt the engine any more than you already have and you can "limp" home).

P0300 is a random mis-fire while P0301-0304 will tell you which cylinder is mis-firing. If it's random you need to check spark plugs, fuel pressure, compression across all the cylinders and the EGR. It's also a good idea to check valve clearance. If you're getting a mis-fire on a specific cylinder you can swap the spark plug and/or injector with another cylinder and if the mis-fire goes to the other cylinder then that's the culprit.

Word of warning: Running that long with a mis-fire you better hope you didn't permanently hurt the engine or need a rebuild.

 

blinking check engine light indicates catalyst damaging events, fix your misfire before you damage anything else.