Originally Posted by
RWTD
The DTC 121 test is generally disabled on vehicles with aftermarket cams anyway. Since we do not have full access to the test parameter for modification, that's generally the only option you have to prevent DTCs and errors.
Also, you should NOT have to disable the other 2 DTCs that were listed. Also, as you stated in your post, try the setting I told you, and go from there. I've had zero issues on the vehicles I've used that on. It's also nearly the same value that Greg Banish did a quick figure on.
If you input the right value, everything else should fall inline, and there really shouldn't be any additional changes needed.