2007 T5 AXE Turbo overboost issue - recommend a Sydney mechanic

[formatview321]

2007 VW T5 AXE (Auto) - 200,000km

The van is now going into limp home mode regularly when driving on the highway or on long climbs.
I have found a few threads on the internet that suggest there could be an issue with the N75 valve, sticky vanes in the turbo.
The possible fixes also include removing the turbo and completely cleaning all carbon build up from around the vanes or simply spraying oven cleaner into the turbo from the exhaust side.


Having a crack at the turbo is above my skill level. I am wondering if I should stick with my local mechanic or if there is a turbo/diesel specialist, etc.. in Sydney that anyone can recommend?


I’ve seen videos of removing, then cleaning the turbo and it’s by no means a quick job. So I’m also wondering if it’s worth it vs replacing with a new part and what the cost of cleaning might be.


I’ve had the car since it was around 70,000km and have driven it conservatively in auto the whole time.

July 2018 - (160k) Noticed that on highway trips when accelerating or using more power the van would very rarely go into “limp home” mode. Turning the ignition on/off resolved this issue.
Jan 2019 - Dropping into ‘limp home mode’ went from a rare issue to a common issue when going up hills on highway drives.
Feb 2019 - Local mechanic had a look and removed and cleaned the EGR valve which apparently had a lot of carbon build up.
The issue didn’t occur for another month but did eventually re-appear.
So for most of this year the van has not been on the highway and when driving around town it doesn’t have a problem.
However now when I drive on the highway or even up a steep hill trying to do 80km/h I can feel that at a certain rev range it is basically guaranteed to go into limp home mode. I can avoid this by slowing down when driving up hills.




The error appears in VAG com as:


Address 01: Engine Labels: Redir Fail!
Part No SW: 070 906 016 BD HW: 028 101 183 5
Component: R5 2,5L EDC G000AG 7001
Revision: 12345678 Serial number: VWZ7Z0F3403165
Coding: 0051075
Shop #: WSC 02756 785 00200
VCID: 53A2A40EF16E08D904-515A
1 Fault Found:
16618 - Boost Pressure Regulation
P0234 - 000 - Limit Exceeded (Overboost Condition) - Intermittent
Freeze Frame:
RPM: 2415 /min
Torque: 400.2 Nm
Speed: 99.0 km/h
Load: 70.2 %
Voltage: 14.14 V
Bin. Bits: 00001000
Absolute Pres.: 2315.4 mbar
Absolute Pres.: 2590.8 mbar
Readiness: 0 0 X X X
Or
Address 01: Engine Labels: Redir Fail!
Part No SW: 070 906 016 BD HW: 028 101 183 5
Component: R5 2,5L EDC G000AG 7001
Revision: 12345678 Serial number: VWZ7Z0F3403165
Coding: 0051075
Shop #: WSC 02756 785 00200
VCID: 53A2A40EF16E08D904-515A
1 Fault Found:
16618 - Boost Pressure Regulation
P0234 - 000 - Limit Exceeded (Overboost Condition) - Intermittent
Freeze Frame:
RPM: 2940 /min
Torque: 395.3 Nm
Speed: 88.0 km/h
Load: 74.1 %
Voltage: 14.21 V
Bin. Bits: 00001000
Absolute Pres.: 2356.2 mbar
Absolute Pres.: 2590.8 mbar
Readiness: 0 0 X X X

I've also seen EGR blanking plates online, would those help with this issue at all?

Cheers

[Umai Naa!!]

Check all vacuum lines.

Also check for excessive play in the actuator on the turbo.

[Rebuild]

you can also reach over the back of the engine with a long bar or screwdriver, and push the actuator to a hard stop, against some pressure.
If it can't reach a hard stop, could be clogged vanes in turbo.

If you get it fixed, don't drive it like a granny everywhere. Give it a reasonable thrashing once a week or so.IMO.

[Silver Caravelle]

I will throw another suggestion into the mix. Clogged or collapsed internals in the particulate filter (DPF). It will cause limp mode ( and flashing yellow light on dash) when accelerating under load due to exhaust restriction. Suggest also ruling this in or out as a possibility.

[Silver Caravelle]

P.S. that's if the 2007 model has a DPF. My 2008 has and I had this happen when it had only done 60,000 kms. DPF was replaced per goodwill from VW as it was not long out of three year warranty.

[formatview321]

Keep the ideas coming all.
I think the vacuum lines are a good place to start, another forum has suggested that the vacuum lines can be a common fault when the VAG com error says "Intermittent" as with mine.

I'm not seeing any error light or flashing lights on the dash when this happens.

I'm also trying to find some info on testing the actuator using VCDS.

[formatview321]

Here is another question.
When I run "Engine -> Output tests", it says that it is testing the N75 'Solenoid Valve'. When testing other valves and solenoids I can hear them clicking on and off from in the car or over the bonnet. Should I be able to hear this valve when it is being turned on/off?

[Silver Caravelle]

If you undo the vacuum pipe that operates the turbo actuator, there will be or should not be any resistance with the actuator movement on the turbo. Install the pipe and the actuator will have a 'resistant vaccum springy feel' when putting a long stick on it to level it.

[DownUnder]

My only Sydney VW mechanic recommendation is Wolfsburgs at St Peters. Looked after my last 2 vans very well and have always been spot on.


Sent from my iPhone using Tapatalk

[scotinoz]

Autobahn Diagnostics in Brookvale

[hotballs]

I had exactly the same thing in my 4motion multivan 2007 model 2.5TDi , it was the particle filter that had broken and 'dammed ' up the exhaust. While apart, the exhaust manifold was replaced as it was warped and the turbo as well, as the garage i bought it from paid the [arts and said while im in there do it. But i am convinced that just emptiing the broken bits out of the particle filter would have cured it.

[miffymiffy]

I have this issue regularly. Im not convinved this is the fix, however it is temporary and works wonders for me.

Pull off the MAF and MAP (or boost pressure) sensors and spray them with brake cleaner. Ones attached to the air box, the other is under the coolant overflow. Clean them up real good. Plug em back in and enjoy the next 15000km...

[formatview321]

The N75 valve is working.
The EGR was cleaned a year ago and looks fine.
The turbo actuator also feels ok.
Cleaned the MAF/MAP - cheers for the tip miffy.


From discussions online and with a specialist VW mechanic it appears to be an issue with ‘sticky vanes’ on the turbo. I have sprayed some oven cleaner into the turbo from the exhaust side and still need to do some driving to determine if this improves things.


One issue I have is that under hard acceleration the intercooler hose popped apart at one of the joints after the EGR and before the intercooler, right under the coolant reservoir. This has led to an endless cloud of black smoke out the back under load, until the pipe is reconnected.


Now, I have seen these EGR blanking plates mentioned and I am wondering if installing a blanking plate would help to alleviate this issue that I am having? Would that stop the excess pressure from the turbo or could that just result in the pressure breaking something else?

[Rebuild]

I tried oven cleaner on mine years ago, don't think it did anything. But then, my turbo wasn't acting up either. Just i had the pipe off, thought i'd try it.
I have an EGR plate in my 2004 AXE, which is a mechanical vacuum operated EGR. It does not throw an engine code.
Blanking the EGR has given a little extra low/mid pull.
Around 2007ish i think T5's went to an electronic EGR. Blanking these EGRs will likely throw an engine code or dash light. Not sure if this can be coded out or overridden. Someone else will likely know. Check which type of EGR valve you have before even trying a plate.
I don't think a plate will fix the issues you are having.

[formatview321]

Yeah I was hoping a blanking plate could at least stop the intercooler hose from bursting.
At this point I've ordered a new N75 valve and MAP sensor just as they a cheap, DIY option to rule out any issues. I'm likely looking at either needing to have the turbo reconditioned or just get a new one.