DIY: Replacing your A4 B6 1.8t front O2 sensor

[Charles.waite]

my question is where does the o2 plug hook up at? when i put in my 034 hfc the o2 wiring got twisted no i have a bank 1 02 fault code so im thinking i broke a wire

It runs along the firewall and connects on the row of plugs on the firewall just to the left of the coolant reservoir when standing in front of the engine. You can't miss them. Its a row of colored plugs.

[CrazyCal]

^
Those stupid plugs. That plastic bracket is brittle. Broke the slot where the crank sensor plug attaches. Grrrrrrrr.