re: sensor2 code,
I had this on my IS300 with 145K and did not see any reduction in mileage, in fact I think its pretty good, not much worse than the SER w/2.0 in town, about 19 vs 21 mpg with same commute, and same on the highway, 26 -27 mpg on longish trips. Did not change the CATS....I used an O2 cheater to remove the code, and passes inspection here in Texas.
2003 Pathfinder from 2004 SE 4WD
1997 SER 5sp Manual from new Rear Ended 2009 !!
Gone to the Knacker yard...
New ride 3.0 manual RWD not a Nissan !!!
1997 Sentra GXE from new .... Sold 2008
2001 Sunny N16 RHD from new (N16 Nissan Bluebird Sylphy) Sold