when the (mil) light came on i checked the codes frum the ecu procedure and found a 0304 code as well as a 0705 code..when i rechecked it today the code was 0505. 0505 means no failure deteced. so what has happend??

 

You probally reset the ECU codes when you tested them the other day, so now a 0505 pops up today. Both of these codes can be intermitant so they may appear time and time again, so test it in another week or so. I had a 0705 popping up randomly for a few months until I got a 0309 and 0705 one day. Which pointed to a bad EVAP canister valve that was causing the problem. I replaced the charcoal canister and EVAP valve and the problem has not come back since.