02 sensor plug
#5
RE: 02 sensor plug
on 2000 EX the primary goes in the downpipe of the header right before the cat and the secondary goes into the cat. There should be a place to thread the o2 sensor in right on the top of the header by the engine and a second spot on the down pipe. You need to plug the top bung and put the o2 sensor on the lower spot.
#7
RE: 02 sensor plug
i know this is an ebay header, but its a good diagram
^ it has lines pointing to the 2 o2 sensor bungs, with the header you should have a gotten a plug for each hole like that picture shows. Plug the top hole and put the primary sensor in the secondary hole farther down the header, then i think you just leave the secondary sensor alone since you've got an EX.