oxygen sensor
 

1997 Cadillac Seville
Does anyone know how to change the B1S1 oxygen sensor. It is at the firewall on top of the manifold, things in the way are heaterbox and crossover pipes.
anyone done this without too much hassle.
my seville randomly throws a P0135 code on cold start

2001 Deville codes P0135,P1860 and C1295 all came on all at the same time. I find it strange that all three codes came up at the same time. The C1295 states that I have an open circuit with the brake lights, but they seem to work just fine, and the car runs just fine as best I can tell. Would three code together indicate something else like a bad computer?
Thanks for any Ideas.