Thanks Mattdavies,
The setup is:-
single turbo conversion
Plug on coil pack
gte Ecu with G-reddy performance piggyback ecu
standard injectors
hks boost controller
there is a fuel/air ratio meter that is working, but I can’t follow the wire from the top sensor to find out where it goes.
the Ecu was changed recently as I went plug on coils, I needed the gte Ecu to run them, but that sensor has always been there,
im only asking because I have an o2 error sensor but i got a new one a few months to try and get rid of the error code, it never worked 