my check engine light is on in my 94 eldorado how do i turn it off
You can't just turn the check engine light off. This denotes an emissions problem. This is merely a symptom that can have have a hundred different causes.
Even if the light were to go out while driving, the problem is still there and a diagnostic code has been set. Having this emissions problem will affect your mileage, power and many different things may happen. Engine may run rough at times, transmission may not shift correctly and other things might not be correct and it all depends on what is wrong that caused the light to come on.
You can purchase a code reader at a parts store. The hand held code reader connects to a port under the dash, under the steering column. By the way, if purchasing the reader, make sure it is for 94 up. 93 and older were a different system.
Now, depending on the reader, it may tell you what is wrong and it may not, but once the bad part is replaced, the code reader should be capable of turning off the light.
If the reader shows code 13, unless it comes with a code chart and their meanings, the reader will not help you.
Now, if the reader shows oxygen sensor, you are all set. You need to ask the parts store what the reader displays.
You have what is known as a hard code with the light not going out. This means that even if you could turn the light off, it will just come right back on without fixing the problem.
The easier and least expensive diagnoses would be to take car to service center (not a dealer) and have them use their reader (scanner) diagnose and get an estimate on the repair.
I wanted to give you 2 options here.
In its current state, the car would not pass an emissions test and will not get peak performance.