If you are referring to the Check Engine light, then it means that the computer has detected a problem with the emissions system. Have the computer scanned to get the code. This code will lead you in the direction of the problem.
The brake light switch is broken or out of adjustment.
There are lots of different reasons a check engine light can come on does the car feel any different?
There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.
brake light switch above the brake pedal
The check gauges light comes on when one of the gauges is not in the safe range.
Check your owners manual
There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.
check your plugs and wires
It means the vehicle will not pass an emission test.
The 'oxygen sensor'may need to be replaced on '96 Sentra when the check engine light comes on. The should be replaced on the '96 Sentra every 100k miles for better fuel efficiency and to protect the converter.
You need to check the transmission gasket between the transmission pan and the body. If it's leaking you have to replace it.
Check ur back light switch:P everyones done it...