Test Pipe Code P0420

[NorthWest Performance]

Hello people....

I have installed a test pipe on a 2000 Impala and have also turned off the code P0420 as well... although I have no check engine light I noticed a couple of my I/M monitors are not "ready", even after weeks of driving.

I also checked codes for the heck of it and I actually pulled a P0420 code out of the PCM, even though I have no check engine light and I turned off that code via HPT! I've swapped back to the stock file, and reloaded the tune file and triple checked my programming.

Does any of this make sense? Shouldn't the PCM see the code is turned off and just pass it by when performing self tests? Am I missing something? This is the first time I've come across this problem.

Any help would be appreciated... Thanks

[S2H]

you have to set it to SES Enabled with "no error reported"
the test should pass after that

[NorthWest Performance]

So I should leave the codes "checked" in the box, but switch to "3 no error" on the right side of the box?

I'm assuming this will let the monitors "ready" themselves as well as no trigger those codes that I set to #3?

Thanks for your input, I figured it was me missing something...

[NorthWest Performance]

I appreciate your help, I just wanted to let you know your advise helped a lot. It passed all the tests, no check engine light, and no codes!

Again, thanks for your help...