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Secondary Air Injection System

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by N80KRR, May 7, 2010.

  1. N80KRR
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    N80KRR Member

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    I read on another forum that you can take this out and place a aluminium plate over it, Juts that mine is going wrong at the moment. Got told it came up with that error about sai and now it saying something about the inlets. Does anyone know anymore on this subject. Sorry for being vague just about all I know.
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  2. N80KRR
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    N80KRR Member

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  3. Q4
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    Q4 Member

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    Having had multiple "secondary air system low flow" fault codes and having the engine mangement light on nearly every other week I decided to get to the bottom of this problem.

    The reason you keep getting this fault is that the lambda probe senses the wrong emmision mixture on start up due to the secondary air flow not being blown through the catalytic convertor. The secondary air system simply blows extra air through the cat to heat it up more quickly at start up for better emissions. The problem is the vacum valve on the back of the head gets corroded through moisture and seizes. Then the secondary air pump itself eventually fills up with water and also seizes.

    So you can take the valve off and block the hole up with the plate but you will always have the engine management light on even after re-setting it and it will come back in days / weeks.

    The other option is to replace the valve (£95 ish) and if your pump is also broken find a second hand one as lots of other VAG cars use the same. Don't bother with a second hand valve as they will all probably be starting to seize up.

    I have yet to come across anyone who can stop the engine management light coming on with the blanking plate fitted unless the bulb has been physically removed.

    Hope this helps.
    .
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  4. dope
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    dope alcoholic pervert

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    I've had this fault for over a year.

    I adjusted the steering wheel height so I can no longer see the engine management light.
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  5. AU01 A4
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    AU01 A4 Member

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    lol
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  6. N80KRR
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    N80KRR Member

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    What would I be searching for to find a pump online? I've tried typing secondary air injection pump but can't seem to find it. Thanks for all the information it is much appreciated.
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  7. Q4
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    Q4 Member

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    Your best bet is to find the part number on your exsisting pump (located low at the front drivers side best seen when under tray is removed.) or use etka online to identify the correct one for your car. There are a few different types with different inlet/outlet locations and different types of plug so you need to make sure of the correct one for your car.

    You can also remove the trim around the front drivers side fog light to gain a bit of visual on the pump. At the same time you can remove the pipe connected to the pump to see if it is full of water as it may be okay and you dont need replacement (the pipe connection is of a squeeze with fingers type/pull off and then just push fit). When the car is started form cold if you listen at the drivers side corner you should hear the pump work every now and then.

    If it is the pump as well as the valve then your best source would be to ring a vw\audi breakers or use the online part search for breakers. As previously posted the pumps are shared with many different VAG cars so you will possibly have to swap the mounting bracket of the replacement pump you get with your original pump bracket.

    Hope this helps.
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  8. Calibar
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    Calibar New Member

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    Hi guys,having the same problem so dismantled the system,the pumps running so i removed all the pipes to the combination valve and on the combination valve theres a hole around the size of a 5p coin should there be a corrosponding hole on the cylinder head ?Hope not because mine doesn't have one,checked all the pipes and they seem ok ,trial and error with the valves i think.
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  9. Q4
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    Q4 Member

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    Hi Calibar,

    There should be a hole on the head where the secondary valve attaches otherwise there would be no need to have the three mounting bolts for the valve. Have a prod around just incase the hole is blocked with some thing making it impossible to see (hole is between the bottom 2 bolt holes).

    With the valve off and the air guide removed (lower half) suck the small vacum point on the side of the silver valve cap and feel with your finger or try to hear the valve move. If it does move then it could be the vacum solenoid control valve under the manifold but it's more often than not the valve on the head seized.

    Just remembered when seperating the valve top from the air guide you will have difficulty geting onto one of the bolts with out a special tool so you can use a good pair of mole grips, not ideal but does the job !

    Hope this helps.
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  10. Calibar
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    Calibar New Member

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    Hi Q4 ,thanks for the reply but it defo doesn't have a hole on the head,took the combi valve back off and checked and theres nowt there,can only assume its not the original engine ,bought the car a year ago and only now has the warning lights came on,think the cars went into limp mode as well as there isn't much power although a month ago it was pretty nippy,aw well looks like it will be parked up for a bit while I try sorting this out,cheers.
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  11. Calibar
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    Calibar New Member

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    Hi guys,managed to source an original head with "the hole" but since it came from a scrapyard and been exposed to the elements would need new valves and tappets but now looking at it I'm thinking would it be possible to drill out a hole in my existing head ?Are there any moving parts inside connected to this valve or is it as it looks and just a deep hole ?This looks like it would be worth an attempt before just swapping heads,whats your thoughts on this.
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