Toyota Repair: 94 Camery service engine light, emission control system, camery

Question
The service engine light has come on my mother's 1994 Camery XLe edition V6 Auto. it has close to 128,000 miles. What could be the cause of this? Is there anything I can replace air-filter, fuel filter, O2 sensor? If so I would appreciate it if you could tell me where they are located.

Answer
The check engine light usually turns on because there is an emission control system malfunction, I can't tell you what it might be because it could be a few different problems, the best way is to have a repair shop or the toyota dealer diagnose the system which will retreive a diagnostic trouble code from the computer, if you can give me this code I can help more.