MK5 Golf GTI

All Things Mk5 => How to Guides / Troubleshooting => Topic started by: FraserMH on October 20, 2025, 08:27:42 am

Title: BWA not making boost
Post by: FraserMH on October 20, 2025, 08:27:42 am

I'm having an issue on my 2008 Octavia vRS with the 2.0TFSI BWA not making any boost. I ran a code scan which showed:

P0100 - Mass or Volume Air Flow Circuit
P0243 - Turbo/Supercharger Wastegate Solonoid A
P0444 - Evaporative Emission System Purge Control Valve Open Ciruit

I installed a new downpipe a few weeks ago and have had my diverter valve unplugged for a few months with no issues.

I also saw a thread from around 5 years ago with the same issues, but it the thread died before an answer. Does anyone have any experience with this issue, or know where to start looking?

Title: Re: BWA not making boost
Post by: GVK on October 20, 2025, 05:38:02 pm

The middle code will be your answer possibly.

It's the N75 valve around the back of the engine that controls boost.

https://www.darksidedevelopments.co.uk/products/pressure-converter-n75-valve-for-vag-2-0-tfsi-petrol-engines.html?srsltid=AfmBOorXNNuYv99XiyNFw6Mu2tEq9Uqe8PknUP29TY0V2rWWZ5x8LOj3