07 3.0 TDI - Code P0046 + Engine Light. Turbo Charger Boost Control Solenoid

[jimmy_c]

Hi all,

First post here and I did post it at another Touareg forum but because there aren't many 3.0 TDIs around outside of Australia I thought I might have more luck here.

Have had a 2007 Facelift (7L6) 3.0 V6 TDI with 165,000kms. Purchased used from a dealer at 115,000km and grabbed an extended used car warranty which the car is still under so I have some hope of getting out of this lightly.

The Story:
Recently the car started acting strangely where it appeared to go into a 'limp mode' but with no engine light present. It would happen very irregularly. Symptoms are it would lose power / ability to accelerate and would also rev really high through the first three gears. i.e. under slow acceleration it would hit 3000 - 3500 RPM (normally shifting at ~2000 or less) with the same agression of driving. It eventually would 'kick out of it' and drive normal once up to speed (about 60kms/h) or if the car was turned off and back on. I've also being doing shocking fuel economy (around 35L/100km+ !!!!)


Last weekend on a short trip of less than 5kms, after getting back in the car to return home the Touareg had the same symptoms but this time had the engine light on. The CEL stayed on since and the car was in this 'limp mode' the whole way home. I haven't driven or started it since because of this state. Today I received one of the cheap Wifi ELM372 ODBII readers. (n.b. The ross-tech is on my wishlist but price + AUD:USD exchange rate + time were factors in acquiring the ELM372). I used two different iPhone apps with the ELM372 and on both readings got the same code: P0046 - Turbo/Super Charger Boost Control Solenoid Circuit Range/Performance.


The problem:
Where to from now?


I'm mechanically minded and have always done my own mechanics on cars and bikes but since acquiring the Touareg, and because of my warranty terms, I have been getting it serviced at the same dealership. I will most likely have to take this to the dealership to fix but I would like to investigate the fault further myself to diagnose exactly what the problem is and have a good idea of what's wrong when the anticipated argument over warranty occurs with the dealer. If it's a simple fix from a bust solenoid or air flow sensor I would probably just fix it myself because the dealership is 50+ km away, it will be a pain to get the car there in it's current state, and I've heard this dealership look for any excuse to get out of their warranty obligations.


Are there any recommendations on how to look into this further (manuals, code translators, diagnostic procedures)?


Thanks in advance.

[Umai Naa!!]

Check the actuator rod on the turbo. Ensure that it moves freely, and apply copper grease on the pivot points.

Clear the fault code, and re-test. Also inspect the vacuum line to the actuator diaphragm, all the way back to the boost control solenoid.

[The One]

As above, I see you're in QLD, which dealership are we talking about? I will probably be able to help you out drastically here..