I have had older cars before, some volvos, but now that i do most of my own work and soon to be an older 240 owner, I would like to know if there is a diagnostic computer on board with codes to isolate issues, and/or can these older 240's be brought to a place ile an Autozone and plugged into their diagnostic tool to see what the issues are?????

 

There is a diagnostics port in the motor compartement, port # 2 is for fuel issues, port #6 for ignition related issues, the manual explains how to identify the error codes.

 

From 1989 the 240 has an on board diagnostic unit.