check engine light blinking

Is the car running really rough? Blinking CELs usually mean a major misfire...to the point the fuel is not burning at all and dumping into your exhaust. Misfires are not a quiet and unnoticable occurrence. Get a tune up done pronto, or better, take it to someone with a diagnostic scanner (not just a code reader) to figure out where it's coming from. A scanner will read everything while running and tell you where it's happening. It's usually cheap for the diagnosis as opposed to more severe engine or catalytic converter damage.

Misfires are also caused by a LACK of fuel too! Have it read for codes, even if the check engine light is NOT on the computer will have stored information and codes. Discount auto stores will read codes for no fee. write them down.