Update 3 - Service engine soon light

Howdy folks - Fell off the wagon for a bit but Im back. I figure I'll share how this was addressed at the end, perhaps it will help a few others with a similar issue.

Turns out the best way to solve this problem ... is to drive around and do nothing about it for 2-3 months! Sounds like I was being lazy I know.  But rest assured, after having visited a couple of different mechanics to consult them on this minor evap emissions leak issue (P0456) , I decided that between the crap they were feeding me (about a full emissions smoke test and possibly finding other issue as well as the cost for the full test etc) and how clearly the issue is not supposed to affect driveability, I figured i didnt have much to lose by waiting it out for a bit to see what happened.

I had this issue last during cooler temperatures (late 2011). Earlier this year, the Check Engine light suddenly disappeared. I rechecked onboard readings using the Scantool and my laptop, and all looked good. it did detect an EVAP minor emissions alert that had not been cleared. That told me that an inspection check might not pass.

Here the Scantool presents a handy utility to erase your error codes. Note that this is different from resetting the ECU. A good quote i found online to describe what erasing error codes really mean is that you are instructing the car to "forget that failure happened and turn off the check engine light". Should the problem persist, the check engine light will reappear after this procedure. the ECU on the other hand observes unique patterns for each car and resetting that might cause it to go back to factory defaults and relearn your cars behavior. Since I am a believer in taking smaller steps before larger ones just to minimize how many things I possibly screw up, I decided erasing error codes and waiting for the light to come back on would be better strategy to make sure it was a real problem showing up.

Anyways, long and short of it is, I erased the error codes, waited a few months to see if the light came back on (it didnt), took it to inspection, and now im good for another year.

moral of the story: if the driveability is not affected directly, you might want to hold on for a bit before taking drastic measures to get an issue fixed. Instead, try smaller actions that might demonstrate whether the issue is recurring or a one time occurrence.

Update 2 - Service engine soon light

Before I delve into how this problem went away, thought id give a quick update on how my trip to the mechanic(s) have gone.

One thing is for sure, mechanics do NOT like hapless customers showing up with Nissan NTBs in hand. It kind of screws with their worldview where you come in, they give you a rundown on all thats wrong with your car and needs a fixin, and you just swallow your pride and submit.

This one guy i went to went as far as asking me where the hell i got the NTB from, and he looked real concerned, he then gave me whole spiel about how although its great theres an NTB which i think specifically solves my specific error code problem with clear directions and workflows from Nissan itself, since he was really experienced hed prefer to run through his battery of tests including the smoke machine etc etc and there was 'a lot of other diagnostics he would have to run' so 'why dont i drop off the car over a couple of days he would check it out'.

I dont know, but sounded a lot like a union guy. not the good kind either.

I hate to rag on the mechanic, im sure some of what he said was legit, but i dont enjoy the feeling when someone gets defensive and will just go into some sort of vague response mode. The fact is, i respect a mechanics ability and trust it more than i do mine - Id even prefer a mechanic to do what i could do, but with his expert hands. But dont BS me.