Should I spend the $65 to buy two new 02 sensors for my 93 when I put the headers in? How can I tell if they are good or not? It only has 43K but figure if I am going to need them in the future why not buy them now, but at the same time I can't waste the $$ if it isn't needed. Any thoughts? Thanks

 

Pull them out and examine them. If they're gunked up and coated (bad) with carbon, I'd replace them. If the carbon build isn't horrendous, I'd leave them. DO NOT attempt to clean them with solvents! A soft plastic type brush and some air would be about it. Basically a good dusting off.

You could also scan the car and see how they do. I don't know what all to look for wrt this method yet as I just got into scanning.. do some searches and see what comes up.