ses light - highway

Alright the problem that Im having now is the Service Engine Sonn light coming on when im driving on the express-way doing speeds between 75mph and 82 mph. Ive tried it without cruise control on nothing gets set off, but when the cruise control is set between 75- and 82 it comes on about 30 - 45 minutes of cruising. it just sounds weird to me. Im wondering if anyone else is having this porblem or had this problem and fixed it. I just want everything to work right before I sell this car.

I know i should just go get the thing scanned but when I get out of work I have to drive to the nearist autozone that is 45 minutes away and also closes at 8 when my work close3s at 8 also. So I just though Id try here first

thanks

I bet it will be a PO420...

and what does that mean?

I have a broken exahust manifold and the leaking piston is 4. If I let the cruise control accelerate the car I would trigger the SES intermetently. I do not remember the code number but my scanner tells me that is a misfire on 4. If this sounds familiar I bet is a misfire on any spark

so do you think that might be my problem or what... did yours act just like mine when your ses like came on? I just dont understand I re built the top end of the engine about 12000 miles ago(all gaskets) and It should not have a problem at all. Its stupid and I need to get ride of it cause its a pain in the azz. let me know

This is a useless post.Your SES lite is on,you know you have a code, have it scanned or spend $35 on a simple code reader. I don't want to sound like a A'hole on this reply, but without some basic diagnosis, nobody can help.

Im just trying to get some ideas on what might be wrong with the car, also seeing if anybody else might have the problem also... like i said i dont have enough time during the day to get the thing scanned... if i get ideas what it it might be... I can check it out myself to see if thats it. If you think this is worthless dont respond in it, just move onto the next thread then... dont mean to be an azz or anything but If i dont have enough time to scan it... how will i fix it, ohh yeah ASK questions to see if anyone else has a problem like mine and maybe have fixed it.