My check engine light has been on for about 6 months and recently turned off without me changing the rear O2 sensor and knocksensor, did the bulb burn out or did my car fix itself?????

 

haha that's funny check the diagnostic code.. if it pops up guess what you have an o2 sensor and a light bulb to replace!

-Vadim

 

what happens is taht sometimes a piece of soot from your engine or wherever will lodge itself onto the o2 sensor. it usually washes out very quickly but nonetheless causes your CEL to come on. its happened to me a couple of times. after X number of start ups that are "trouble free" the ECU will assume that everything is OK and turn the engine light off. my code, as of now, is 0505. check yours. i bet its the same.