O2 Sensor Voltage To Lean Out

[InADream]

I tried posting this in the General forum but got no answer so ill try it here...

I have a 2002 Chevy S10 and I just added an HHO Unit.. I want to add a voltage enhancer to lean out the fuel mixture... Here is my dilemma, a few weeks ago my Check Engine Light came on... After getting it read by autozone they said that both of my pre cat sensors are bad... Now here is my question...

Do I need to replace the O2 Sensors before adding the enhancer or can I just leave them alone and add the enhancer... If I am reading the instructions to the enhancer correctly, by adding the unit I am bypassing the O2 sensor to begin with... Please correct me if I am wrong?

thanks love the site

Dan