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Fuel Trim Bank 1: System Too Lean Fault

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by mrjheeta, Aug 19, 2009.

  1. mrjheeta
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    mrjheeta Member

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    Hi all,

    Got a problem with the car, been going on for a while now.

    Did a scan with VAG-COM, with the results i've tried searching on here but have not come up with a solution.

    Any ideas? I really would love to get this sorted because it's coming up everyday now and its really doing my nut in!!!


    VAG-COM Version: Release 409.1-S

    Control Module Part Number: 8E0 906 018 B
    Component and/or Version: 1.8L R4/5VT 0003
    Software Coding: 11501
    Work Shop Code: WSC 63351

    1 Fault Found:
    17536 - Fuel Trim: Bank 1 (Mult): System too Lean
    P1128 - 35-00 - -


    I've gone on the vagcom wiki, it does give information, but I was hoping somebody may be able to tell me where I can start. I've got the whole day tomorrow to sort this. I've also noticed that the car is going through a lot more fuel than before (about 40 miles from 9 litres of petrol, and I drive like an old lady!) and is lacking power.

    Thank you in advance for your help!

    G.
    #1
  2. Q4
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    Q4 Member

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    At a guess it sounds like the good old MAFF sensor has gone belly up, or a Lamda probe (o2 sensor) as you say your fuel economy has got worse.

    If the MAFF is playing up then the car's performance will also be down.

    The easiest thing to try first is a new MAFF which is easy to replace yourself. I would at this point disconnect the battery for a "system reset" and do the self throttle body alignment at the same time.

    If that does not cure it then the next step wouldl be to replace the Lamda probes.


    Good Luck !
    #2
  3. Xmay4444
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    Xmay4444 On Point!!

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    Ckeck your vacum hoses as well.
    If they are split they may also give thise kind of readings.
    Good luck
    #3
  4. mrjheeta
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    mrjheeta Member

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    thanks guys, all the vacuum hoses are fine as i've had one of them replaced already at my last service. im going to go down the new MAF route tomorrow, does anybody know of a right up of how to replace/change the MAF? thanks for your replies guys!
    #4
  5. technics100
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    technics100 Member

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    yeah, I had this on my 1.8T bora, it was a boost leak from a split hose. with the car running have a good squeeze at all the hoses etc and listen for leaks, also some people spray a fairy liquid and water over the engine to see bubble when the leak blows through. You can also pressure test it with a DIY kit...
    #5
  6. mrjheeta
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    mrjheeta Member

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    cheers guys, i've got the old MAF out, just gonna pop down to GSF and pick up a new one (although reconditioned). I'll check with this first, then check all the hoses again, I'll take it down to my local independent and get them to pressure test it. I was hoping to get this sorted as I needed my car all day tomorrow, and didnt fancy carrying my laptop around with me.
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  7. technics100
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    technics100 Member

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    I would try and buy a new one, try trade part specialists they do original bosch items, they will just want your old maf as trade in.. I got one for my S6 for £65..
    #7
  8. mrjheeta
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    mrjheeta Member

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    i did try the bosch dealers, but they just told me the same thing, they said that we will take your old one as exchange as most are refurbished units anyway. so i've picked it up, fitted it in, gonna do the throttle body alignment, and give it a test!
    #8
  9. mrjheeta
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    mrjheeta Member

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    ok so i took the car out for a test run, on first start up it seemed to have a complete different sound! i took the air filter out n gave it a clean while it was open so that may have something to do with it. at first glance, it seemed to be a different car! i took it out on the A404, closest A road to me, and it definitely did move! yesterday i was struggling to get anywhere, but today definitely shifted! so it looks like it may be the MAF but I will know for sure in the next few days when i drive it more and whether or not the engine light comes on.

    if it does come back on, then god only knows! back to the garage for that...

    thanks for your help though, very much appreciated guys!

    G.
    #9

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