I am having service engine soon light on.I took the car to 3 service stations but all of them said to repair different parts. The charges differed a lot among them. Some said to change rear O2 sensor for $200 and some asked me $350 for that(O2 sensor). Some of my frns suggesed me to take it to SEARS and I took it.A guy gave me the codes like po600, po430 and po128 and told me to take it to nissan showroom. I got this car before a month frm a friend. Suggest me what I have to do now. Zip 05401.