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.


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[scotinoz]

Autobahn Diagnostics in Brookvale