I just got my 02 civic and now it was throwing codes for bad o2 then it went away when i changed the o2s now it says 'catayltic deficency'.

Anyone know how many cats a 02 4dr EX has? or what i could do to dump that code?

 

You can try put in a fouler on the o2

 

i tried that and i ran fuel system cleaner through it. Anyone know which cat typically fails first and how many thier are?

 

hmm maybe someone can refer me to another forum or something?

 

I do know that there is only one cat on any Civic. On an EX it will be under the car, the second O2 sensor screws into it. You could take the back pipe off at the flange and look inside the cat to see if someone has hollowed it out.

 

what yr is yours?

 

it looks like theres one thats connected to the manifold and another one in line with the exhaust pipes to the tailpipes

 

double up on the fouler and install on the 2nd o2 after the cat.

 

what is fouler is it the same as fuel system cleaner? how do i use fouler?

 

The bulge in the pipe under the back seat area is just a resonator. The cat is between the firewall and the shift handle.