When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
main o2 is BEFORE cat (it is in exhaust manifold).
there is diagnostic procedure at service manualt to determine with one (left or right is dead)
I had that problem and change oxy semsor. in my car driver side was dead.
If you stuck I can help you tomorrow.
Jerry
you can buy universal oxy sensor, just must rewire it to original harness.
I am living in Poland
25 code is main oxy sensor (left or right) lean condition. in my car it mean that one main oxy was dead.
if you want replace both mains there is no need for determine with one is dead. Just replace both. use universal ntk or another good quality oxy sensor. rewire it to stock wiring harness. that is quite easy.