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Audi A4 1.8T - Error Code P0171

  • 01-05-2009 6:06pm
    #1
    dodzy
    Registered Users, Registered Users 2 Posts: 10,153 ✭✭✭✭


    Hi All,

    The dreaded CEL lit up the other day so I pulled the error code using an OBDII Scan tool. P0171 - Running lean on Bank 1.

    Inspected for leaks in the vacuum lines ( before moving onto the MAF / O2 Sensor ) and I heard a noticeable "hiss" coming from the rear of the block, directly above the Coolant Temp Sensor.

    It turns out that it is coming from what I think is a pressure control valve ( see attachment ) P/N: 06A 129 101 A.

    Could it be the culprit ???


Comments

  • #2
    Neilw
    Registered Users, Registered Users 2 Posts: 3,795 ✭✭✭Neilw


    It would help if you could get the car scanned with vag-com, it will show the full fault code.

    16555/P0171/000369 - Fuel Trim; Bank 1: System Too Lean
    Possible Causes

    * Mass Air Flow Sensor (G70) defective

    Possible Solutions

    * Check Mass Air Flow Sensor (G70)
    * Check Fuel Pressure Regulation
    * Check Fuel Pump
    * Check Injectors
    * Check Intake System for Leaks
    * Check Exhaust System for Leaks
    * Check Secondary Air System for Leaks
    * Check Vacuum Pipes for Leaks


  • #3
    dodzy
    Registered Users, Registered Users 2 Posts: 10,153 ✭✭✭✭dodzy


    Neilw wrote: »
    It would help if you could get the car scanned with vag-com, it will show the full fault code.

    16555/P0171/000369 - Fuel Trim; Bank 1: System Too Lean
    Possible Causes

    * Mass Air Flow Sensor (G70) defective

    Possible Solutions

    * Check Mass Air Flow Sensor (G70)
    * Check Fuel Pressure Regulation
    * Check Fuel Pump
    * Check Injectors
    * Check Intake System for Leaks
    * Check Exhaust System for Leaks
    * Check Secondary Air System for Leaks
    * Check Vacuum Pipes for Leaks

    Cheers Neilw

    I've been threatening to get myself the VAG-COM for ages. The OBD tool is a poor substitute. That aside, the list of "potential" faults listed with the VAG is extensive and I'm guessing but i'd say that some faults i.e MAF / vacuum leak are more common than others such as fuel pump / injectors.

    I'd still like to know why the PCV I mentioned earlier is sucking in air though. Ah well, at least she's mobile ;) Thank God.


  • #4
    Neilw
    Registered Users, Registered Users 2 Posts: 3,795 ✭✭✭Neilw


    dodzy wrote: »
    Cheers Neilw

    I've been threatening to get myself the VAG-COM for ages. The OBD tool is a poor substitute. That aside, the list of "potential" faults listed with the VAG is extensive and I'm guessing but i'd say that some faults i.e MAF / vacuum leak are more common than others such as fuel pump / injectors.

    I'd still like to know why the PCV I mentioned earlier is sucking in air though. Ah well, at least she's mobile ;) Thank God.

    I'd say it a vacuum pipe somewhere, give them a check to see if there are any splits. Some of the ones under the intake manifold are prone to splitting.

    Neil.


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