Engine light does not come off. indicates a transmission problem after repaired

Thank you for your reply. The mechanics said something to the effect that it was dirty/gunky but I still need a rebuilt transmission. Does the fluid need to be changed often? I've been going to the same mechanic that replaced the solenoid for my maintenance. My car runs fine. I drive it on the freeway everyday, is fast, no noises, drives uphill without problems. I don't get it. I really need the light off because it will not pass smog.