You know I have been getting this problem alot lately myself. Here's my story. . . . .
Last Thursday I get gas and everything is ok when I start my car and do my usual deeds. Friday, I go to work, 47 miles, and everything is ok. Then when I go on lunch break all of a sudden my '05 (12k miles) throws CEL. So I freak out b/c my new '05 is throwing CEL and I haven't done one d@/\/\n mod to it yet! I research and call Nissan and finally mess with the gas tank cap. Exactly 24 hrs later, Saturday, the CEL light goes off. As for the gas tank cap, I am an all or nothing guy, I would either close my tank or leave that thing hanging outside of my car after I leave the gas station.
This past Friday, same thing happens again. but this time I got gas earlier and ever since last week I make my gas tank click at least 10 times just so I can avoid that CEL light. So this light is on again. WTH, I haven't done a damn thing to the car either and this $h1t is on once again. So I go by the dealership where I purchased the car and I guess since I look young and only 24 they brush me off with the, "Check your gas tank cap!" But they Tech does acknowledge that I told him that isn't the problem and how I made that cap click "many a times" but blows me off and says drive it over the weekend, "ECU take about 30 starts to reprogram!" But I kinda did that myself when I saw the light come back on, so I just cut my car off and then back on at least 20 times but no results. Still CEL (SES)! I said that it is ridiculous for a SES light to be coming on this early in a brand new '05 Z and they said, "Well no it's not if it's finding something." And I'm thinking to myself "D@/\/\N I am so stupid I forgot that when you buy a brand new car that you will get issues just like a used one, what am I thinking this is all normal stuff for new cars(sarcasim)" So pissed off at this point , I pulled myself away before getting irate and go get the codes off of my ECU from a local shop. I bring it back to them and ask them about the codes for feedback but they just tell me to leave my car and they will look at it in 2 days. At this point when I drove my car back to the dealership, my TCS OFF light was on along with my Slip Diff. and I couldn't get out of second gear and speed was no faster than 30mph. And do you think they even glanced out the car, there was a tech standing outside chatting at the time but not even a glance at the car! Maybe I was asking too much for them to just glance at the car for feedback. . . . . . even thought I know it wasn't too much! Basically the engine codes I got dealt with my MAF and the TPS sensors. Not sure the issue but the light is off now! Ah just had to get that off of my chest!