Is the Altima in trouble?

So last night what looks like a “Check Engine” light came on on the Altima‘s dash.
I just called up the closest Nissan dealer, Gettel. Unfortunately they’re closed till Monday! d’Oh. I guess I’ll be calling back then. For the time being, the manual goes on to recommend that I don’t exceed speeds of 72km/hr, and, if possible, I should “avoid hard acceleration or deceleration”. This is not going to be easy!