Hi All,

I've got a 2017 2.0 TDI 190 BHP DSG sportline.  A couple of times now over the last 2- 3 week when I've dropped the DSG into Sport and hit the accelerator to overtake a car I get a flashing coil light and the car goes into limp mode.  Stop the car and restart the flashing coil light goes out and car goes back to driving normal.

 

I did a quick scan with Carista and have the code P029900, Turbo Charger Under Boost.

 

Doing a bit of searching / googling I've found a couple of possibilities:

 

1. A check valve on the vacuum line: 

 

2. Turbo actuator: 

 

Any other ideas what it could be before taking the car to the Indy?

 

I'm planning on trying 1. above as it's only a few quid for the part and an easy change.

 

Thanks.

Anybody?

This coil is the glow plugs relay block - normally would need a diagnostics to determine better.

I scanned the car for codes.  The one I got was: P029900, Turbo Charger Under Boost

Boost pipe leak perhaps.

Hi @ MunsterScot

 

How did you resolve this issue? As i have had the same problem come up yesterday. Thanks 

Hi @Ali1  I reset the code and put some Forte Advanced Diesel Treatment and Forte Diesel Turbo Cleaner in the fuel and ran it for a while (links below.  You can buy it on Amazon as motor factors don't usually stock it as it is supposed to be trade only).  Code has only come back the  once.  I think for me, but could be wrong, the issue I have is the wife drives the car most of the time (80 miles a day 5 days a week) and she doesn't drive very fast or accelerate very hard so the vanes on the turbo don't really get a chance to open / move very much.  So when I dropped the car into sport and put the for down the vanes on the turbo were sticky so I got an under boost error.  As mentioned, I could be wrong but the code has only came back the once a few month later.

 

I've also started using dipetane  regularly to see if that helps.

 

A few years ago I had the same boost issue on a Mini Copper S (completely different engine I know).  With it I when through checking inlet boost pipes, turbo actuator play, valves linked to turbo pressure.  In the end with the Cooper S it turned out to be a blocked CAT causing too much back pressure.  New CAT and all good.   

 

Have you scanned the car to see what error codes you have?

 

https://www.forteuk.co.uk/product/advanced-formula-diesel-treatment/

 

https://www.forteuk.co.uk/product/diesel-turbo-cleaner/

 

https://dipetane.com/

 

https://forums.tdiclub.com/index.php?threads/code-p0299-turbo-underboost-resolution-repository.271408/

Thanks pal.

 

Yeah so I've got the same car as you. 2017 Skoda Superb 2017 dsg 4x4 190bhp. Same turbo under boost code as well

@MunsterScot  “I reset the code and put some Forte Advanced Diesel Treatment and Forte Diesel Turbo Cleaner in the fuel and ran it for a while “
 

Above is a great tip - have used other Forte products many years ago and always good results. 
Just ordered the twin pack for £23.39 on ebay to use as preventative maintenance on my steadily driven diesel.   (It usually gets filled with Esso supreme or Shell V power to try to help keep the internals clean but this Forte stuff can only help. )