check engine light

In Nov. '03 my the motor on my '97 Buick Park Avenue seized (the person who changed motors said it was because of a crease in the oil pan obviously caused in a previous incident prior to my buying the car; should have
checked it out thoroughly in retrospect). Anyway, the motor installed was said to be '95 Olds (3.8 liter; same size as the original). My question is what would cause the check engine light to come on intermittently? This has occurred since Dec. '03. That is, it goes off after some long periods and comes on after hundreds of miles of driving ... making it wholly unreliable, I would guess. Could it be that the install of the replacement motor was not done correctly or could it be that the replacement motor is not wholly compatible with the Park Avenue circuitry? It would be greatly appreciated if anyone with insight can answer this.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You'll need to have the codes scanned to see what triggered the light. Places like Autozone and Pep Boys will do that free of charge I'm told. The code will be stored in the computer. May be something as simple as a loose connection on an O2 sensor. FWIW YMMV DFB
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.