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Discussion Starter · #1 ·
hi the Emission control light on in my 2.0tdi, its a 2004 year, i had it serviced by audi a week and half ago, does anyone know what it can be, its done 53k on the clock

just been to my local garage, they pluged in there hand held dianogtic system and 2 faults came up one was a electric fault in cylender 2 (glow plug) which i was aware of as audi dealers told me when i serviced it and the second one was code 16618 Boost Pressure Regulation: Limit Exceeded (Overboost Condition) something which i was told ,anyone got views on it, he checked for loose connection found 1 with the air fitler pipe the one that goes in the engine, that was not put on correctly,and he also found that one of the pipes was worn thin by rubbing against the engine cover, oh and he resetted the fault, and said if it comes back on come back, so if he has resetted the fault if something is wrong will the Emission control light come back on?

has anyone else had this fault code 16618
 

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FIrst of all mate i would clear the fault codes and see does anything come up again.....

but as regards the 16618 issue it suggests to me the wastegate actuator could be buggered or the N75 boost control valve which controls the wastegate is buggered.

Either of those does NOT mean a replacement turbo unit.

If both those items are broken in some way, it means it can no longer control the boost provided by the Turbo. The fact its overboosting means turbo is actually working fine (it is creating boost). It is simply creating too much as the wastegate is not being opened to release some exhaust gas on the hot side of the turbo to limit the speed the compressor wheel is spinning at.

If the wastegate itself is buggered which is part of the exhaust side of the turbo then that can be fixed I would have thought without needing a whole new turbo.
 

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But i would wait and see if fault codes re-appear after those hoses being re-attatched!
 

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Discussion Starter · #4 ·
thanks for the tips mate, great help,so how would i know if any of the following things you said is buggered?
 

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Discussion Starter · #5 ·
i had the fault cleared, so if there is a fault how soon will the emission light come back up again?
 

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Hopefully connecting that loose vacuum hose will fix the problem for you mate and you wont have any faults coming up again.

I would continue driving as normal and see if the emission light comes back on again... if he found the root cause of the problem you may be in the clear! sometimes it can just be the simple things[Y]
 

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Discussion Starter · #7 ·
thanks mate, i dont know if it was the vacuum hose, i not too good with the engine parts names, but it was i thick black pipe that connects to the back of the engine, you can see it without removing the engine cover, i just hope its noting major or a expensive job, fingers crossed
 

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Discussion Starter · #8 ·
ok the light has not showed up, but when i drive there is so much lack of power, it does not pull over 2-3 rpms
 

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By the sounds of it mate you are in limp mode. Can you run Vagcom to see what fault codes come up. Can you turn the car off and then start it again without the problem?
 

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Discussion Starter · #10 ·
well when i turn off the engime it runs back to normal. went and had it diagnos again and the same fault came up, and one for clyender 2 glow plug, the chap said to fix the glow plug one first as it is cheapist
 

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You see when u turn off the car and turn it back on again the engine no longer runs in limp mode. Limp home mode is a safe mode so that you cant do any more damage, It is obhiously overboosting and as a result producing this fault and limp mode. Its the wastegate actuator or the N75 boost control valve that has had it.

A fault with the glow plug in C2 wont have any affect on it....it prob has to be done sometime but its not going to cure your problem
 

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Id say mate that its the N75. They are around £40 iirc. How is the car behaving now?
 

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Another thing it can be is the Variable vanes on the turbo getting stuck as a resullt of a build up of carbon. It could be any of these things but its another possibility.........
 

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If you want to check the vanes.... disconnect the actuator (circlip) and move the little VNT lever on the turbo. It should flick back and forth freely and with a bit of a clonk. If it feels tight or crunchy then the vanes are being restricted by the build up
 

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Discussion Starter · #17 ·
the car is behaving like normal, but i know it will go back to the limp mode, i better get it sorted, i got it booked with these guys tommorow, http://centralaudivw.co.uk/ for the faulty glow plug, and they going to reset the 16618 fault code and take it from there, when i had it diagnosed by them i asked them what it can be , i cant remember what they said but he phoned the VAG guy they deal with for parts and he said that part alone will cost £172, but they said before any change of parts they going to look into more detail
 

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Discussion Starter · #18 ·
ok here is a little update, had the glow plug changed, and they found oil leak, looked into it and found out that its the fuel pump thats leaking
 

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hmmmm that sounds separate mate to ur ongoing problem? is the 16618 still coming up with the new glow plug?
 

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Discussion Starter · #20 ·
there is no faults codes at the monment , but i will have to run the car for few days to see if it comes back up again, but soon as they replaced the glow plug and cleared the faults at took it for a run and checked it again there was no faults coming up, now for the fuel pump they qouted £235 for the pump and £155 for labour, went to audi told them the problem about the fuel pump they said £235 for the pump and £189 for the labour,but they said we will have to have a diagnostic but said might include if i take there offer on,
 
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