O2 Sensor "too Much Activity"

[2003 ImpalaLS]

I have a 2003 Impala with 3800 series II. I have replaced the single exhaust with Dual cat backs (gm performance parts exhaust) and a 3" Hogan front downpipe with hi-flow cat. I also run a K&N intake. When I installed the downpipe, the engine light came on and the problem it says is too much activity on the #2 oxygen sensor (located next to cat). The fellow I bought this pipe from said he had the same problem with this pipe on his Grand Prix. Is there a fix for this? I have currently installed an O2 simulator (basically a sleeve that draws the sensor out of the pipe a bit) and I still have the same code. What is my best bet?

Thanks in advance

[Iflylow]

There is an O2 sim available that allows you to remove the O2 sensor entirely, and it simulates the signal for the PCM. I'll try to find a website for you.

Never mind, Hemi beat me to it, thanks!

[HeMi101]

https://www.zzperformance.com/grand_...=834&catid=110

[Blue Bowtie]

For reference, this is basically normal upstream activity on a 231 V-6: