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Rear (post cat) lambda sensors. what do they do? where to buy?

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by fourcircle, Jun 16, 2011.

  1. fourcircle
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    fourcircle nj

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    [Jun 16, 2011]
    One of my rear lambdas needs changed. Now I can get them for about £100 each from audi or maybe about £75 for bosch direct fit replacements if I go elsewhere. The things is... Are the post cat lambdas used for adjusting the fuel mix or just for measuring the cat efficiency (ultimately to let me know when they're knackered)? I would entertain getting a couple of eml eliminators since I know the cats are fairly new if my £200 will just be wasted on sensors that will tell me my cats are buggered... which should be in a good 100,000 miles I would hope :)

    Any answers, advice, recommendations for sellers or witty anecdotes about nuns and penguins would be welcomed
    cheers
    nj
    #1
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  3. audigeezA4
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    audigeezA4 Member

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    [Jun 16, 2011]

    hi mate
    in my unlimited capacity of limited knowledge of what you are on about, something about lambs and cats????
    i thought i would make myself useful and offer you my useless reply to your question, which clearly is not of any use....... :uhm:
    yours cluelessly.
    :unsure:
    #2
  4. dsmclark40v
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    dsmclark40v Member

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    [Jun 17, 2011]
    Rear sensors are just to make sure the cats are working, the front ones adjust the fuel trims. Some tuners can make the car ignore the rear sensors so it doesn't throw a code. So could be an excuse for a remap if you don't already have one!
    Sam
    #3
  5. fourcircle
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    fourcircle nj

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    [Jun 17, 2011]
    :) thanks for that. it is indeed a vetinary themed discussion, specifically regarding lambs and cats and whether one will affect the fuelling of my car. I know, same old story..
    #4
  6. fourcircle
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    fourcircle nj

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    [Jun 17, 2011]
    Cheers Sam. a remap you say? hmmmm.... :) I don't know if i'd get much out of it on my 3.0 N/A. What do you think? If I could VCDS the rear lambdas off that would be the simplest thing. I can't see how to sell the remap to the missus as a cost saving to avoid buying a new lambda sensor.. could be tricky.
    #5
  7. hades-
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    hades- Yorkshire & Humber Rep. Regional Rep VCDS Map User

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    [Jun 17, 2011]
    remap is not worth the cash on a n/a you cant code them out via VCDS
    id go for the ELM
    #6
  8. audigeezA4
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    audigeezA4 Member

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    [Jun 17, 2011]

    ;)hope you get it sorted mate, one way or the other, otherwise i know the number of a good vet....:doctor:
    #7
  9. fourcircle
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    fourcircle nj

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    [Jun 17, 2011]
    how did I not notice before that we had a fisting smiley?
    #8
  10. fourcircle
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    fourcircle nj

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    [Jun 17, 2011]
    Thought that was the case. I'll go research the light eliminator doohickey
    #9

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