P0420 code...O2 sensor?

[Screaming Monkey]

Hey guys just need a little help here. (checked the sticky O2 sensors)

background:

-2000 saab 9-3 viggen

-p0420 code Catalyst System Efficiency Below Threshold bank 1

-the car has what looks like a relatively new exhaust all the way from the down pipe(magnaflow, and I assume its new-ish because there is no rust on the piping at all I'm guessing within 2 years it was installed)

-My converter doesn't rattle or glow red at all when revving.

-while ac is on and I accelerate onto the freeway(second gear) its like my car hits a brick wall at 50mph, 5000-5500 rpms. it just stops and you can hear the engine wanting to rev more. I shift up the car vibrates like crazy i need to coast a little while then all is well. when the ac is off however, it function just fine.

- also with ac on it doesnt happen in 1st, or third. I'm too chicken to try 5000k rpm in 4th

- I am noticing some low mpgs. its struggling to get 22mpg most of the time around town and only about 25-26 free way. i believe that's supposed to be 23-24 town and 27-30 freeway

-no clue if this is relevant but i also have clickly injector on cold start ups or when the ac is on
any suggestions would be appreciated!


took it to my mechanic about an hour ago he thinks its the upstream O2 sensor which brings my to the second bit which one should I buy. I know it has to with the vin, but I have no idea what all the numbers mean.

- last digits of vin are xxxx7003342

[mcbxkk]

Hi, i have similar problem on my 9-5 MY2000 2.3, did you solve this problem? thx

[Trionic3000]

It's either the catalytic converter or the 02 sensors, both posts.