What Check Engine Light trouble codes were downloaded ? The Evap System is fairly basic, and competent mechanic, or persistent Jeep owner should be able to find the failed or hose or fitting.
Incompetent, Ignorant, or lazy mechanics always blame the CPU for problems they can't, or won't diagnose. I suggest you find a more skilled and resourceful mechanic. CPU failure is very highly unlikely, and an Evap issues certainly would not cause the CPU to fail.
Progressive Liberalism: Bringing you new ideas so wonderful, they have to include mandatory participation ......
Originally Posted by Ronald W. Reagan: Government is not the solution to our problem; Government is the problem.