Anyone with experience changing out the O2 sensors on an 1994 XJ12?

I have no reason to think mine need changing out, but I am just trying to think of what might get the fuel economy up a little. Also, at 102K I can imagine that a PO may have let the change out at 90K go by the wayside.

Here are a few questions:
1. Is there a way to know if they really need to be replaced?
2. Where are they most easily replaced from?
3. Do I need to use OEM parts or will something generic work?
4. Is there anything else I should check while I am doing this work?

Thanks for any input.

reb

If you have a voltmeter you can test them.

As far as I know your model has garden variety 3-wire sensors. You might wanna talk to a Jag parts specialist to verify that.

You don't have to use OEM.

Cheers
DD