Hi, it's not about Nissan but Mazda; I have both Nissan and Mazda and I have
no place to ask about Mazda though...

I noticed my 88 Mazda 323 turns her check engine light while idling long
time enough (maybe 10 mins?)... it is not always and I saw this happened
twice until today - the first one 3 weeks ago, and the last one today.
I started engine went back to my apartment, and then came back to find the
light on. I just stopped the engine and re-started engine again - the light
goes away.

Could it have something to do with cooling system? it takes a little bit
long to reach normal temperature ever since I replaced radiator cap -
actually it puzzled me but I didn't care.

any idea,please let me know. Thank you in advance for your help!

SJ