I have a 2005 evo 8 throwing 2 codes. P0141 Oxygen sensor Heater circuit bank 1 sensor 2 and p0170 Fuel trim bank 1. P0170 is upstream o2 sensor, is that the one located in the turbo outlet pipe 02 housing? I'm unsure what to do about the other code any help would be awesome thanks in advance.

 

Font O2 in the O2 housing... it can cause a P0170 as well

 

P0141 is sensor 2 after the CAT. If that's so it has minimal effect on performance but it can point to CAT issues/exhaust leaks ECT. P0170 is a lean code. Get back on the scan tool and ensure O2 sensor 1 is switching properly. Are you getting performance issues? Did you delete pcv hose or have CAI?