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Help with P0420 fault code

Discussion in 'A3/S3/Sportback (8P Chassis)' started by armstrong_21490, Jul 30, 2014.

  1. armstrong_21490
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    armstrong_21490 Member

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    [Jul 30, 2014]
    I am getting the following fault code p0420 catalyst system below threshold

    I was wondering if anyone has had any dealings with this code and what is causing it?

    I have cleared the code but it comes back on after a while.

    Cheers

    Ross
    Last edited: Jul 30, 2014
    #1
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  3. mechanic69
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    mechanic69 Active Member

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    [Jul 30, 2014]
    Ross-Tech Wiki post this info:

    16786/P0402/001026 - Exhaust Gas Recirculation (EGR): Excessive Flow

    Possible Symptoms
    Malfunction Indicator Light (MIL) ON
    Reduced Exhaust Gas Recirculation (EGR)
    Reduced Power Output/Engine running rough
    Increased Emissions

    Possible Causes
    Exhaust Gas Recirculation (EGR) Valve stuck open/leaking/faulty
    Exhaust Gas Recirculation (EGR) System leaking/faulty
    Wiring and/or Connector(s) from/to Exhaust Gas Recirculation (EGR) Valve faulty
    Possible Solutions

    Check/Clean Exhaust Gas Recirculation (EGR) System
    Check/Replace Exhaust Gas Recirculation (EGR) Valve
    Check Wiring and/or Connector(s) from/to Exhaust Gas Recirculation (EGR) Valve
    #2
  4. armstrong_21490
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    armstrong_21490 Member

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    [Jul 30, 2014]
    Sorry bud I just realised i had put the wrong code in the title. I've changed it now.
    #3

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