Nissan Repair: 2000 Altima potential broken computer..., computer scanner, nissan dealer

Question
Hello. My 2000 Altima's check engine light came on in February. When I brought it to my mechanic, he ran a computer scan and replaced the knock sensor. A week later, the check engine light came on again and my mechanic couldn't find the cause after running the car several times throughout the day. He turned the light off and I took the car back. About 2 weeks later, the check engine light came back on. When I brought the car in to the mechanic again, he still couldn't find the cause. He tried his 3 computers on it and concluded that the computer in my car is not working properly because it's not giving him any codes despite the light being on. The light has turned on again, but my car seems to be running just fine (no noises, smells, stalls, etc...). Do I need to take this car to a Nissan dealer and get the computer fixed/replaced or should I just keep an eye and an ear out for any malfunctions the good old fashioned way? I'm afraid that replacing the computer will not be worth the expense. Is it time to get a different car? Thanks for your help!

Answer
Mimi,

The problem should not be the computer.  I would pull the connector down where the computer scanner hooks to your car to see if there are bent pins or ones that have slipped out.  Go to Autozone or Checker and have them check the codes for free and email me back with what they find.