My 04 Express flashes the check engine light after about 15 minutes of driving, the light does not stay on, it just flashes, 20 times, then 5 times, then 15 times, drive another 10 minutes, flashes 15 times, then 20, etc... no real pattern, but always 5, 15 or 20 flashes, code on obd P0300 random misfire, multiple cyl, obd will not pin point any one cyl. Does the number of flashes give any clues as to what is going on, or why is it always the same # of flashes, I'm stumped,

 

the flash count is meaningless. the fact that the mil is flashing signifies you have a misfire condition that is damaging the catalytic convertor. get it fixed immediately before the cats are destroyed.

flash out codes are a obd1 pre 1996 diagnostic.

 

Check engine light "on" means get the car checked soon. Check engine light "flashing" means take it in now!