Ok i just recently purchased a 03 wrx which i am happy with but one problem... the cel on. Now, the codes i am getting are p0130 and p0031. They told me that these codes indicate the front o2sensor. I immediately assumed it was bad so i bought the cheap universal bosch brand. I placed it on the car with the battery off and the dam cel is still on. (it went out for about 10 seconds than it came off. Now i again went to the store and told them this and they said i needed to run the car for about 0 to 500 miles. I went on a couple forums and they said as soon as you plug it in with the battery off it should remove the cel and not come back on. Can anyone please tell me what is wrong or what i need to do? i was going to take to subaru but i know they charge alot for any little problem. any type of help and comments will be greatly appreciated it. Thank You