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New exhaust system fitted last week and now I have fault code! Code inside...

DJ_Troopa Jan 18, 2010

  1. DJ_Troopa

    DJ_Troopa K1 Driver

    Hi everyone

    Had a custom Longlife exhaust system fitted last week with a 200 cell sports cat from Style Dynamix who are down the road from me. My engine management light came up 2 days ago so i got it on my mates VAG-COM this evening and this is what it said..........

    VAG-COM Version: Release 311.2-N

    Control Module Part Number: 8N0 906 018 J
    Component and/or Version: 1.8L R4/5VT 0004
    Software Coding: 10710
    Work Shop Code: WSC 13622
    Additional Info: WAUZZZ8LX21001067 AUZ7Z0A1890544
    1 Fault Found:
    16804 - Catalyst System: Bank 1: Efficiency Below Threshold
    P0420 - 35-00 - -

    I've known the company for years and are very good so they won't mess me about with any problems. If somebody can point me in the right direction to resolve this i would really appreciate it!

    My friend has cleared the fault off for now but i'm assuming it will return again at some point!

    Thanks, hope you're all well :)

  2. S3 Paul

    S3 Paul Well-Known Member Regional Rep

    I think bank 1 means the lambda probe before the cat. Might be wrong though,
    I would check the wires to both the probs. and the plugs.
  3. DJ_Troopa

    DJ_Troopa K1 Driver

    Cheers Paul, going to my exhaust guys tomorrow to check it out.

    I found this on Ross Wiki, what's your thoughts people?

    16804/P0420/001056 - Catalyst System; Bank 1: Efficiency Below Threshold

    Possible Causes

    • Leakage in Intake and/or Exhaust System
    • Catalyst faulty
    • Oxygen Sensor(s) faulty
    • Oxygen Sensor(s) Control faulty
    Possible Solutions

    • Check Intake and Exhaust System for Leaks
    • Check Catalyst
    • Check Oxygen Sensor(s)
    • Check Oxygen Sensor(s) Control
      • Perform Oxygen Sensor(s) Aging Check
  4. <tuffty/>

    <tuffty/> Badger 5 Edition...Its all about the flow... Staff Member Moderator Audi S3

    Classic fault code for sports cats.... the sports cat is less efficient than the OEM/std cat and the ECU thinks the cat has seem better days. The second Lambda is only really there to check the efficiency of the cat really so you can ignore it or try and get the supplier of any remap you may have to to code out the probe.

  5. S3 Paul

    S3 Paul Well-Known Member Regional Rep

    I think i once saw an exhaust where the second lambda was sat away from the exhaust abit , fitted in a slight take off. so tricking the second lambda into getting a better reading.
  6. DJ_Troopa

    DJ_Troopa K1 Driver

    So if my light comes back on again with this fault, can i ignore it? Will it affect performance or the car in any way? That's the last thing i want happening! Thing is, it'll be hard to ignore with that bloomin light on and when the fault is wiped again it'll come back again after a while wouldn't it?

    Thanks for that info!

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