Nissan Repair: check engin light, sensors and actuators, vacuum leak

Question
I have A 1997 NISSAN XE PICK UP WITH 105000 MILES ON IT. Service engine soon light is on.It is a 4 cylinder. Where are these sensors and can i change the one that is bad my self and how do i know which one is bad?

Answer
First, we need to get the trouble codes out of the computer's memory to see what may be the problem. There are a few sensors and actuators that each has a different job to do. Also, another important thing is that if a sensor trips the check engine light, it doesn't mean that the sensor itself is bad! For example, if there is a vacuum leak, the oxygen sensor will detect a lean mixture and it will trip the light. But replacing the sensor will simply not fix the problem if we don't fix the vacuum leak first! Please, take the car to a technician or take it to Autozone. The latter can use a scan tool to extract the trouble codes for free! Then, we'll take it from there.