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  1. #1
    Active Member One Ring kob1801's Avatar
    Join Date
    Dec 03 2017
    AZ Member #
    Honolulu Hawaii

    Upstream O2 Sensor Replacement

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    I have a 2008 B7 A4 Quattro 2.0t and I am trying to replace my upstream O2 we sensor. The problem I'm running into is that when I follow the lead from the sensory seems to disappear into a wireing harness behind the engine, but I can't really tell. Any help with this would be appreciated.

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  2. #2
    Veteran Member Four Rings Andrew149's Avatar
    Join Date
    Apr 19 2009
    AZ Member #

    Use a mirror with a flashlight.

    Sent from my iPhone using Tapatalk Pro
    2008 Audi A4 Avant 2.0t 6speed
    JHM K04 tune, JHM Full B6 S4 exhaust system, JHM HPFP UPGRADE, JHM RS4 clutch, JHM Shifter Knob, S3 Injectors, S3 K04 Turbo, RS4 Grille, RS4 RSB, H&R Sport Spring, K&N, Bilstein Sport Shocks, Snub Mount, AWE Boost Gauge, 034 motor mounts, 034 Transmission mount, 15mm Rear Spacers, 12mm Front Spacers, Audi TT wheels, Recaro B6 S4 Seats, Mt90 Trans oil.

  3. #3
    Established Member Two Rings
    Join Date
    Apr 24 2015
    AZ Member #
    San Diego, CA

    Itís routed behind the engine and terminates to a connector mounted to the firewall, which is behind the coolant reservoir.
    I canít recall if the upstream sensor is brown or black connector.
    Itís a bit of a pain to remove it from the wiring bundle that is traveling with it due to visibility.

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  4. #4
    Veteran Member Four Rings Audibot's Avatar
    Join Date
    May 20 2010
    AZ Member #
    Items for Sale

    I believe the upstream one is the black connector.

  5. #5
    Senior Member Four Rings Okedokey's Avatar
    Join Date
    Oct 24 2015
    AZ Member #
    Perth, WA

    I run mine over the engine cover towards the back. Is there any reason that could be a problem that anyone knows of?
    A4 B7 2.0T | HPFP upgrade + FMIC | BSR Stage II + exhaust + HFC | 3.0TFSI Throt. Body | RS4 fuel contr., PRV + S3 inj., G247 + DW300c | GFB DV+| 034 RSB + all arms and mounts | S4 brakes | B12 Bilstein suspension + H&R springs | RNS-E + Polk Audio PA D5000.5 - 4 x DB6502 + DB840DVC sub + Pioneer 10" sub | LEDs throughout | 19" Audi 2015 RS4 rims

    My respray thread


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