2003 - 150 tdi overboost - richiek
Hi all,

Just a few weeks after having a new head fitted to my ARL I now have an issue with the turbo. It went into limp home mode the other day but has driven fine since. I had it plugged into VAG diagnostic today and the error code revealed the turbo was overboosting. They said the cheapest option was to replace the boost valve as this sometimes cures the problem. Personally, I think it may be sooted up as it was over-fueling before the head change and chucking out black smoke so replacing the turbo is more likely but I can't afford that on top of what's already been done recently so I'll have to sell the car.

Is there a cheaper solution anyone?

Edited by Dynamic Dave on 31/12/2007 at 20:44

Golf 150 tdi overboost - Screwloose

Which code did you get - 17965?
Golf 150 tdi overboost - richiek
Not sure to be honest didn't think to ask but they said it was an overboost code.
Golf 150 tdi overboost - Screwloose

Could be the boost pressure sensor; the N75 solenoid; the vacuum hoses - or the turbo coked up.

Even if it's that; just get them to clean it - recon turbos are often more trouble than they're worth.
Golf 150 tdi overboost - richiek
Is the boost pressure sensor the same as the boost valve they mentioned about changing? I mentioned about it being coked up but they didn't seem to like the idea of stripping it down to clean it. I'll try to find out the exact fault code on Wednesday. Is there anything I can do myself such as a relatively easy way of unclogging it?
Golf 150 tdi overboost - Screwloose

No; the boost pressure sensor is akin to a MAP sensor and measures the pressure in the intake pipework.

The N75 solenoid valve adjusts the vacuum to the turbo's actuator capsule under pulse control from the ECU.

They don't seem very clued-up if they're thinking of just changing parts at random without testing anything first - not even the vacuum levels.

There's no easy way of unclogging coked vanes; just remove and separate the turbo and use combustion chamber [oven] cleaner and a variety of scrapers. These turbos are getting on for £1000 fitted - it's got to be worth an hour's cleaning.
Golf 150 tdi overboost - richiek
I would be glad to give it an hours cleaning but don't really know how to take it off. Do you have to take off the manifold? There is an odd noise when I accelerate like a sort of quiet slurping - not tubo whistle - which may point to a vacuum hose I would have thought.

When they put the new head on they mentioned that the connections on a couple of the intake pipes on the turbo looked a bit ropey and the pipes could do with replacing. When I asked them yesterday if slight faults in these could cause overboosting they said no. Like you say, they don't seem very clued up.
Golf 150 tdi overboost - Screwloose

I was thinking more about paying them an hour's labour. There is a great link to a picture sequence on here somewhere that explains all.

I can't get search to work at all; so I can't find it for you. Hang on; think it's in one of my favourites folders....

It was:-


However; test first - repair later.
Golf 150 tdi overboost - richiek
The link is very good but I wouldn't fancy stripping it down like that in case I messed it up? Can't you just clean the vanes with it assembled?

Do you think that odd noise I can hear on acceleration could be a damaged vacuum pipe? I'm getting very cheesed off with this car now especially having just spent 2 grand on having a new head fitted. I'm considering just selling it as it is since it still drives fine apart from that odd noise which you can only hear if you are listening for it.

Edited by richiek on 01/01/2008 at 18:43

Golf 150 tdi overboost - Screwloose

Odd noises under load are often the pipe joints leaking. That would give sub-target boost [underboost] not overboost - are you sure they diagnosed this correctly?
Golf 150 tdi overboost - richiek
I will try to find out the error code tomorrow and then post it on here after work. Would underboost send the car into limp home mode though?
Golf 150 tdi overboost - Screwloose
That's a - very definite - yes!

Edited by Screwloose on 01/01/2008 at 19:28

Golf 150 tdi overboost - richiek
That would make sense then as when I picked up the car after having the new head fitted I couldn't believe how much quicker it was. Now it doesn't seem quite as quick and I don't think it's just me getting used to it either.

Couple that with the noises I'm hearing on acceleration and them warning that the pipes didn't look too good I would think underboost is more likely than overboost although they were convinced it was an overboost code. I'll try to find out the exact code.

Any idea of the cost of replacing those pipes and how big of a job it is?
Golf 150 tdi overboost - Screwloose

It's often just a clip rather then the pipe itself and impossible to guess where it's leaking - if it is.

Confirm the code before doing anything else.
Golf 150 tdi overboost - richiek
Apparently the code was 17965. Does this help?
Golf 150 tdi overboost - Screwloose

That is indeed an overboost code; get them to test the movement and function of the turbo actuator and the vacuum level from the solenoid when controlled by the scanner.
Golf 150 tdi overboost - 659FBE
Good advice of course, but you can connect a piece of rubber tubing to the VNT actuator capsule (remove existing pipe first - push, don't pull) and exercise the system by mouth suction.

With the engine stopped, a really good hard suck should move the actuator rod about 20mm. You can feel this if you put your fingers under the capsule where the operating rod emerges. Put your tongue over the pipe end at full suction and check that the actuator is held at the fully pulled-in position (max boost). This checks the actuator diaphragm for leaks. Release the vacuum and the rod should gently return fully - it doesn't give a "click" like the EGR valve. Any failure to return smoothly or consistently will give an overboost when the engine is under load.

Golf 150 tdi overboost - richiek
Do you know what diametre rubber tubing I need to use for this? How will I know if it's the turbo itself that's at fault or something else?

Someone mentioned the boost valve or sensor could be a likely cause.

It's been very lumpy for about 10-15 secs when you first start it in the mornings since the time it went into limp home mode although it still starts on the first turn of the key. Sometimes I need to give it a little bit of gas for it to pick up. Do you think this problem is related?
Golf 150 tdi overboost - 659FBE
Screwloose has given you the best advice. If you want to try a little self-help, try my method above. It's not infallible, but it will test for a stuck VNT or a holed actuator diaphragm.

If you are going to take the self-help route you will have to get your hands dirty. Remove the vac pipe to the actuator and have a look. (It's about 3mm dia).

If there are other running problems and you have eliminated the overboost, get the codes read and find someone who can act on the information logically (preferably an independent VAG specialist).

Golf 150 tdi overboost - richiek
Seems like my turbo is knackered but I know someone who is selling one off a golf 130 that only had 26k on the clock. Can anyone tell me if the 130 turbo will fit the 150?
Golf 150 tdi overboost - Screwloose

How can a turbo be knackered and yet be producing too much boost....? If it's the turbo; then it must be stuck vanes.
Golf 150 tdi overboost - richiek
When you rev the engine right up with the bonnet up there's a right odd tinny noise coming from the area where the turbo is. My mate who was MOT'ing my car at the time said it sounded like the turbo was knackered but I thought, if that was the case surely it would be chucking out loads of smoke which it aint.

One other thing is, when I've been driving up the steep hill towards my road after work the last few days I can smell that eggy smell the cat produces now and again. Don't know if this could affect the performance of the turbo at all though.

No-one I've spoken to wants to take off the turbo and have a try at cleaning it unfortunately that's why I thought about buying the 130 one which I could get hold of if it will fit mine.

Edited by richiek on 10/01/2008 at 18:28

Golf 150 tdi overboost - Screwloose

Although it could be the turbo making that noise; many turbos are replaced due to resonating heatshields or the shaft nut comes off and rattles around on the turbine like a demented Roulette ball. [Have a look - something may have dropped in when the head was off.]

Incorrect boost might well mess up the fuelling and give noxious emissions.

As to whether the 130 and 150 turbos are interchangable - that's one of those things that you only find out the hard way.
Golf 150 tdi overboost - 659FBE
Unless you try a bit more self-help and check the parts lists. They are on the Internet.

2003 - 150 tdi overboost - hm

If you live anywhere near Leicester I'm willing to give you a hand to take look..........


2003 - 150 tdi overboost - richiek
Thanks for that mate - really kind of you but I live in Devon. Cheers anyway.
2003 - 150 tdi overboost - hm
mate, have you tried moving the VNT....I have a post somewhere where I fixed my mates passat (srewloose, still going well :0)

Did you determine that none of your pipe were leaking? have you manually tried to move the VNT lever arm with a screwdriver or similar? does it move freely? have you tried the 'suck' method yet..the diameter of the will be about 5/6mm internal...like windscreen washer hose......

Checked the nut has not come off turbine like Mr Loose said (you just need to undo a hose)

Actually checked to see if the turbo is boosting using a vacume gauge.......

I'm still convinced you have a clogged up turbo...and removing the turbo is not really a big deal....

2003 - 150 tdi overboost - richiek
Thanks H. The only thing I have determined is that none of the pipes are leaking.

As for the VNT lever arm and the rest of what you said I'm afriad I'm not really competant at those things or even know where they are.

I really need to have it looked at by someone who knows what they are talking about. All the so called experts round here are interested in doing is fitting a new - or second hand - turbo.
2003 - 150 tdi overboost - hm
yea I bet they are..then all they will do is spend and hour cleaning your old out and unit swap it with someone else's...and at £700plus a time it is a nice little earner......

I apologies now to any legitmate mech's out there.......... :0)

As for your question about the 130 and 150 turbo I really do not know...I would simply check the partnumbers.....if they have all the same fitting etc I would find it hard to believe that would be different as the BHP increase is all about fueling etc, not boost pressure.

sorry I can not help further...may I suggest if you do not know of a good garage by you, you do search on one of the tdi sites and ask there.



2003 - 150 tdi overboost - rich-m
Hi mate, I have exactly the same problem as yourself. I have the same Golf and I can confirm that what the diag kit throws up (over boost) is correct. It does this, as far as i know, because the turbo (the nozzels) are blocekd and the boost is being lost.

Mine has lost lots of power and I have been told that my Turbo will need sending to a specialist to stripped and the nozzels to be cleaned.

I'm really not into mechanics and stuff so my question is, is there any other way around this (and a cheaper way)?

Its really getting to me as the Golf is running on about 60% power it seems. Just what neeeds to be done to get it back to normal, is it over fuelling also and will a new temp senor solve things slightly.

2003 - 150 tdi overboost - perleman
I know this sounds obvious but are there any good VW specialists near you - people who will work for £50 an hour, will know Golfs like the back of their hands, and who will be friendly & polite? If you get on the Golf & VR6 forums and ask for a recomendation maybe? If the turbo only needs cleaning you could prob get it done for under £100.
2003 - 150 tdi overboost - Raman
richiek , don't konw if this will help but you might want to telephone these guys

They are far from you. But might offer some useful advice.

2003 - 150 tdi overboost - Screwloose

It's never a good idea to jump to conclusions over code 17965. [There are no nozzles in these; just variable vanes that can stick.]

Yes; it may be the turbo; [50/50 chance] but it can also be a lot of other things and it's a pig to get at the turbo and then to find - after a big bill - that it's just the same.... because it was just a perished little rubber hose all the time.
2003 - 150 tdi overboost - rich-m
Thanks Screwloose,

I have asked a mate who is quite up on VW stuff and he said the same as you about there not being and 'nozzels'.

I have been quoted a hugh price by the garage and it didnt seem to take them long to say 'oh yes, thats the turbo faulty'? It will need to be sent away for cleaning by a specialist company they tell me.

They also said it was the Actuator sticking, and after they vacumed(?) and worked it, it worked a bit better.

Any help or ideas on this you can pass on will be much appreciated, I could really do without that hugh bill.

2003 - 150 tdi overboost - Screwloose

If it's been professionally diagnosed as a sticking vane ring; then that's rather different. If the actuator is sticking when vacuum is applied, then it's sticking - game over.

An actuator is the correct term for what would be a wastegate on a conventional turbo. Have a look at that link in one of the posts above to see what they mean - at least they're doing the right thing and sending it for cleaning and not fitting a rubbish re-con.
2003 - 150 tdi overboost - rich-m
When I say its sticking, what they did, helped it and they say they could see it freeing up slightly but its still not right.

So are you saying that stripping it down and sending the turbo away is the pretty much the only option I have?

I mean, if I pay all this money to get it done, is it likely to happen again or is that it? Is this a common problem,?

If it is I've absolutley had it with VW. My golf has cost me more in repairs then anything else I've owned. Its depressing.

2003 - 150 tdi overboost - Screwloose

Will it happen again? Not for quite a while.

Yes. Cleaning is the best option. Very common problem.

Golf IV costing you fortunes - quite normal. Most victims will never have another VW.
2003 - 150 tdi overboost - rich-m
This is really getting confusing, some folk I speak to say they have never heard of a turbo needing sending away for cleaning and its pointles and theres some on here that say yes it needs doing and is the only option. Can I not just replace the actuator that seems to be at the center of all this?

I mean, are VW really that bad that a part is that flawed that when it gets dirty or clogged-up, it has to be sent away and you have no option but to pay half a grand to get it 'cleaned'.

If this is the case then surely its a design fault on their part and they need to recall them or contribute towards the cost. It really doesnt make any sense to me, it just doesnt sound right, not one bit.

Has anyone lese sent theirs away?

Edited by rich-m on 12/02/2008 at 12:26

2003 - 150 tdi overboost - 659FBE
The actuator fitted to the Garrett VNT turbochargers of this vintage is a very simple vacuum capsule - rather like a giant version of the device which used to be fitted to the side of distributors to advance the ignition timing. These seem to give very little trouble and can be tested in a rough and ready fashion by sucking hard on a piece of tubing pushed on to the vacuum connection.

The difficulty lies in the vanes which the actuator has to move - they live in the turbine housing. As such, they are exposed to high temperatures and sooty exhaust and can be prone to seizure. It is the cleaning and freeing of the pivots for the variable vanes which is done when a turbocharger is "cleaned". Given fair general maintenance (oil changes) and considerate treatment, the rotating part of Garrett turbochargers seems to give very little trouble when used on most diesel engines.

It has been proposed that a good "engine workout" from time to time will keep the VNT vanes free. I'm doubtful about this because full boost can be demanded at relatively modest engine outputs (eg WOT at low crank speeds) thus exercising the actuation system throughout its range.

When I give my PD 130 a service, I do attach a piece of tubing to the actuator and check the movement of the VNT system (you can feel the actuating rod underneath with your fingers) - there should be about 20mm of movement with a really good hard suck. Placing your tongue over the end of the pipe will also check for a leaking actuator diaphragm.

One day, I may re-plumb my PD so that the VNT is moved throughout its full stroke whenever the engine is shut down - using the vac signal for the anti-shudder valve.


2003 - 150 tdi overboost - rich-m
Is there anyone who can help me with finding where the actuator is so that I can at least try and work it to free it up. As one of the posters above said, this has worked before and is a last effort before spending £500 on having a garage strip it down and send it off.

2003 - 150 tdi overboost - nortones2
There's a link to an illustration of the turbo and actuator posted above: you should be able work out where it is with a printed-off image!

Edited by nortones2 on 16/02/2008 at 12:58

2003 - 150 tdi overboost - hector1975
I had same problem with my 150hp Golf. the vanes were stuck on the turbo causing it to overboost. Actually fitted a gauge on the inlet manifold and it was blowing at something like 22 psi before the engine shut down.

Really need the car on a proper ramp to do anything. If you look up at the turbo you will see a vacuum actuator attached to it. Now with the engine running attach and disconnect the vacuum supply pipe and not how far the actuator rod moves. Bear in mind that the vacuum signal is high at idle (vanes in 'aggressive' position) and tends to zero at full boost (vanes closed to reduce boost).
Now disconnect the vac supply and see if the arm moves back to its stop. To check give the rod a little push with the end of a screwdriver. Be careful though because its easy to knock of the clip on end of the rod. You will probably find that the arm will feel stiff and move slighty back to its stop. It needs to be free enough to move into this position under the actuators pressure otherwise the turbo will overboost .
I guess if you work the rod like this it's possible you might free it off - worth a try. 130 hp and 150 hp turbo's are different i was told (different part numbers anyway). I tried a rebuilt turbo to start with but it was faulty so I would personally pay another £100 and get a new garrett turbo.
2003 - 150 tdi overboost - rich-m
Thanks Hector and Nortones,

I have looked at the diagram and it doesnt really mean much to me im afraid, it doesnt explain how to get to the actuator. When I took it to a local garage, they worked the actuator with a hand vacuum and this did free it up quite a bit, without getting it up on the ramps.

My plan is to do exactly the same bit work it a bit more and see if this frees it up. Im just not convinced that this vanes cleaning is totally the problem and trying something that costs nothing has got to be worth a try. Its my last chance before I resign to spending £500 at a garage and getting it cleaned.

Can this be done without it going up ramps, also does anyone know of a garage in the Staffordshire area that could simply strip the turbo without sending it away and cleaning the vanes there?

2003 - 150 tdi overboost - Screwloose

Your garage appears to have done a competent job of diagnosis and has made the only reasonable suggestion.

As you admit that you don't even know what the parts look like - let alone appreciate the grief involved in getting then off; then why not accept the good advice and let the garage do as it advised.

How many garage workshops do you think are equipped with turbo-cleaning kit like walnut-shell blast cabinets? You can't clean a vane ring properly with turps and a toothbrush.
2003 - 150 tdi overboost - nortones2
The first PHOTO (not a diagram!) in this shows the parts- www.technologie-entwicklung.de/Gasturbines/VNT15-T...l

2003 - 150 tdi overboost - hm
if you are anywhere near South Leicestershire let me know.. I can give you have hand (Jct 20 M1)

2003 - 150 tdi overboost - jbcomputerservices

Hello. I have a 2002 plate 1.9 tdi not long bought it, got a sticky actuator and over boost. Theold boy that had before me drove it gently so i think i have the dreaded vains sticking

2003 - 150 tdi overboost - The-Mechanic

Follow the instructions of this link :


I used this guide to sort out the sticking vanes on my Seat Leon (similar, if not identical to yours). Mines still running fine after 10 months so it's we'll worth trying it for what it costs.

Good luck and post back if it helps.


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