I read on another forum that the upstream and downstream o2 sensors are the same in functionality. Is this true? Looking at o2 sensors online they don't always mention if they are up or down stream, but they are quite a bit cheaper for even the same brands.

Also, does anyone have an opinion on a good brand cat converter? I don't really want to put a test pipe on there. Two brands I have commonly seen are Magnaflow(with positive reviews) and I think the other was "Eastern" or something along those lines. Any opinions or those or, again, any others?

Thanks, guys.

 

Is your OEM cat messed up?

The 2 sensors are absolutely different. The primary sensor (before cat) is used to measure the amount of oxygen in the exhaust, and sends signals to the ECU in order to adjust A/F ratio accordingly. The secondary sensor (after cat) is mainly there just to verify that the catalytic converter is in place and operating correctly.

Everywhere I've looked shows the secondary O2 being quite a bit more expensive than the primary O2, for whatever reason. But the primary one is really the only one you need to replace if you suspect it's causing poor fuel economy (provided the secondary one isn't throwing any codes).

I recommend Denso-brand O2 sensors for Hondas. Bosch ones usually seem to not work or hold up as well.

 

Well long story short, my o2 sensor shorted and blew a whole out of the side of the tip. As far as I know it also blew apart the inside of the cat because Acura told me that pieces were flying out of my exhaust. I have an aftermarket exhaust, so this is believable in my eyes. They told me I need a new o2 sensor and cat. I am 99% sure its the downstream sensor.

Thanks for the tip on the sensor. My post about the car is somewhere on the forum.. probably back a few pages if you wanna know more about the o2 sensor thing. I updated the whole situation on that post.

Any ideas on the cat brand?

 

really have no idea on cats