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Non obd cat

Discussion in 'A4/S4 forum(B5 Chassis)' started by audiv6quattro, May 29, 2011.

  1. audiv6quattro
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    audiv6quattro Member

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    [May 29, 2011]
    Hi all I need another new cat (left side this time) but does it matter if it's a non obd part as I'm pretty sure my car (a a4 2.6 v6 quattro 1997)has onboard diagnostics.thanks alot for any replys
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  3. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [May 29, 2011]
    This is another one of these retarded things that parts companies come up with, along with "canbus" compatible light bulbs.

    All B5's have OBD (on board diagnostics). This has absolutely NOTHING to do with the catalytic converters.

    What the retards are actaully getting at, is that later cars have two lambda sensors one before and one after the cat, allowing the car to perform diagnostics as to the health of the cat.

    Your car will have one lambda sensor. This means you probably want a "non-obd" cat.
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  4. audiv6quattro
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    audiv6quattro Member

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    [May 29, 2011]
    Ok thanks alot aragorn thought it was a bit funny that only some places only mentioned the non obd part.I've found one for £120+vat is that about the right price or is there a company that could possibly be cheaper.thanks again
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  5. HenryL
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    HenryL New Member

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    [Feb 7, 2012]
    Hello Audi people -
    Clarification about the discussion in this thread about "non-OBD" when it comes to buying a downpipe/cat (mine is a 2000/X-reg A4 B5 V6 non-quattro 2.4 SE (manual)).
    I have the same question about whether a 'non-OBD' part is OK. I've got fault codes o420 and 0430 for 'cat below efficiency threshold' which suggested to me that the car must be 'OBD', though when I looked underneath I only noticed one sensor, right in front of the cat (but at the time I wasn't searching for sensors, so there could perhaps have been one lurking further back down out of site after the cat I suppose). Unfortunately I can't get to the car at the moment but need to chase up the parts...
    Cheers
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 7, 2012]
    That fault code implies you have two lambdas, meaning you need the "OBD" version.

    There should be one lambda right up beside the exhaust manifold, then another down under the car after the cat.
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  7. HenryL
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    HenryL New Member

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    [Feb 7, 2012]
    Hi Aragorn - thanks for that - 'OBD'/dual sensor it is then. The sensors are still a slightly worrying puzzle though. Unless I am completely losing my marbles there was a sensor just in front of the cat box. The section of exhaust seemed to be 3-bolted to what looked like manifold flange at the front end, then a bit of pipe (with hanger bracket fittings) then a flexible joint then a short run into the cat box with a sensor fitted in it just before the cat. Could this be something else other than an O2 sensor? I had got the impression from somewhere else (re 2.8 engine possibly) that the 1st sensor would be up at the manifold somewhere, but then I don't know what I was seeing stuck in the pipe.
    Unfortunately I didn't get down and look round the back end of the cat at the time, so to speak :)
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