So i bought my 02 corolla about a year ago, and it's had the same code almost the whole time. Its the system too lean bank 1. I was told it is usually a vacuum leak but could be a number of different things. It's had a tune up and has been kept in great running condition. It had the oil burning issue and has been rebuilt as of 4k miles ago, CEL still on. About a month ago i found a vacuum leak at an injector, replaced all of the seals, it ran WAY better but still had CEL. Last week a cleaned the MAF sensor, it ran even better, and it wen't off for about a day and then come back on. Same code every time. The fact that it went off makes me think it might have something to do with the sensor. I also thought that maybe one of my O2 sensors is bad or even my CAT from burning a quart of oil through it every week. Also, my car has made a high pitched whistling noise since the day i bought it which usually indicated a vacuum leak. It's coming from my throttle body and changes pitch when you hit the gas.(vacuum leak right?) but my mechanic told me that on some of the these cars the throttle body will naturally make a whistling noise... is he full of shit? Sorry for the long windedness Thanks for any input Chris Added: Mar 3, 2012 1:37 AM PS i need to pass smog in a month. uuuuuuuuuuuuuuuuuuuuuuuck!