[Biturbos4] Engine DTC help request

[Ti Kan]

Keman writes:
> So tell me, has your local fuel station started using ethanol?
> Or.. perhaps.. more ethanol?
> 
> Ethanol's stoic is around 9-10:1. As opposed to what we call "gasoline" 
> which is around 14.7:1.
> 
> For a given mixture, the O2 sensor will see it as running lean the more 
> ethanol you use, and try to richen it up.
> ...

I usually fill up with Chevron supreme but occasionally get Valero or
Union 76.  I would have no idea what's in the gas.

-Ti