Hi I just purchased a 98 cherokee 4cyl. For some reason the previous owner had the o2 sensor in the first section of the exhaust hanging down unplugged. Where exactly does the sensor plug in to? Thanks

Here's a picture to make things easier. This is how it looks from the front of the car. Where do I plug this in?

 

the top of the manifold, that where mine is.

 

Is it easier to do from under the hood? Can you be more specific I work a lot and don't really have time to go under the car and guess. Pictures would be great! Thanks for your help.

 

1 on the exhaust manifold. the other on top of the catalytic convertor. Do the job from under it. Spray it with penetrant well. Both are in hot locations.