With innovate controllers the sensor usually hasnt failed, they just refuse to work when the frequency response gets slower. If you get error 2 or error 8 the sensor is likely still perfectly fine and will work with any other wideband controller, if you haven't thrown away already, save them as spares for when you have a decent controller.
Innovate determine oxygen content by driving the sensor completely differently than they were ever designed to be, rather than measuring the actual pump current required to keep the nerst cell near stoich they instead drive the pump at full current all the time, continuously bouncing current backward and forwards, then use the resulting duty cycle to derive how rich or lean it was. This can give very fast response and works fine when the sensor is new, clean, and its temperature is relatively stable, but age, temperature and deposits effect the timing a lot so the controller then justs reports the sensor has failed if it takes too long to see the response it expects.
For what it's worth, I wrote up my experience of setting up knock control on my Impreza STI 2007. It's all based on the Link help files... I believe what I have done is correct (comments welcome!) Feel free to have a look at the attached word doc...
BTW, I found the sound levels of each cylinder to be quite 'noisy', so had to have a fairly large headroom in threshold to prevent false knock detection.
Knock Setup.docx
