Quick question that I have had for a while.. Does the 2ND 02 sensor change afr in closed loop instead of 'just' reading the cat? I know some cars do but I'm not sure if the Evo's do or not. Has anybody tested this?

 

It's only for measuring cat effectiveness.

 

Tested? How did you find out?

 

You can disable it with zero ill-effects.

 

^100% Factual

 

Alright. Thanks guys!