Just Got my CAT replacments.. Qs????
Thread Starter
TECH Regular
Joined: Nov 2003
Posts: 488
Likes: 0
From: Bay Area/ UCI-VDC norte
Just Got my CAT replacments.. Qs???? I just recieved my set of pipes to replace my cats... my question is on the longer one y is there an opening... is it for the 02 sensor? isnt that y i bought 02 simms? should i fill it or re-install the 02 sensor and the 02 sims? im confused. Another prob is can i just unbolt the cats and theyll drop, or will i have to unbolt the entire exhaust?
10 Second Club
Joined: Nov 2002
Posts: 1,471
Likes: 3
From: Berkeley, California
Normally our cars have four oxygen sensors, one upstream of the cat and one downstream on each side. The two upstream sensors are essential. With cats removed, simulators replace the downstream sensors.
If you got the Mufflex by-pass pipes, the driver side pipe will have a hole for the front 02 sensor. On the stock catted pipe, the 02 sensor is on the pipe with the cat. So when you take the stock cat off, the sensor comes with it. You will need to transfer the sensor over. On the passenger side, the sensor is on the manifold just above the 3-bolt flange. So when you take that cat off, the sensor doesn't come off with it....which is the reason why only one of the pipes has the hole in it. 
