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.
left side is bank one, right side bank two. in 99% of cars, bank one is the side where #1 cylinder is. 1/1 is sensor one, bank one, 2/1 is sensor two, bank one, etc. Or sensor 1 is upstream, sensor two is downstream.