How to fix overboost for VW Tiguan 2009?

Question

With a Tiguan when I go on 5 or 6 gear, I often get blinking light and reduced power. Then I can stop car, start it again, it works again.

So I noticed that it happens more often when there is a load for the engine. Like if I go 130 kmh on 6th gean when there is no hill, it goes ok. When there is a hill, often I get the error and lose power. In rare cases this happens on 4th gear.

My service diagnosed that there is overboost error and the car turn on service mode. Service says need to remove turbine and bring it to another service which has stand to diagnoze.

I have read here that it is easy to fix:

What is overboost?

So how to fix that? My service is planning to remove the turbine and bring it to the stand for diagnosis and then will see what to do. But according to that answer in the link, looks like there is no need for a stand. So is this the case really or for Tiguan still need to diagnose with the stand? Service said there is a posibility that I will need turbine restoration.

Update

Service took turbine to the stand, and said turbine is ok, no need restration and replaced the thing which controls how much air to let in. So valve probably. The problem still exists - I am getting error and losing power when that light is blinking. Will call shop tommorow, probably they will say to bring car for diagnostics again and see what it will show.

Here is the paper from the stand:

Update

The shop said there can be badly programmed computer after DPF filter was removed. So they called a programmer to reprogram it and it did not help.

They themselves do not know what else to do besides changing the turbine but looks like they are not confident about that also, they said they will discuss and let me know what they decided.

What else can be done? Is there a chance that changing turbine will help even after the stand showed it is working ok?

Answer 1

That model has a turbocharger with two valves. Using the parts diagram from here:

VW Tiguan Turbo Parts Diagram

You can see callouts 10 and 12:

These are the "cutoff" valve and the "boost relief" valves. These are both electrically and pressure controlled valves that are designed to prevent the overboost condition.

In your case you need to determine which is having the problem and then either repair or replace it. A shop with a diagnostic stand will be able to determine which is the problem but you likely have no access to one, so you'll need to find out yourself.

My guess is that it's #12 as these types of valves can get clogged up with gunk and stop working. You may be able to clean it out with some carb cleaner. If all else fails, replace both.