2009 Opel GT 2.0 T - P2261

[XploD]

Hello to everyone!
About one year ago I bought this car (Saturn Sky Redline in the States), mainly to track it.
I've gone through all of the issues it was facing, until now, that I can't get rid of the P2261 DTC.

I replaced the BPV solenoid and checked the vacuum lines, as well as the diaphragm, and I can see no issues. This car has no vacuum tank.
I have the suspicion that the ECU has been tuned.

The last day I went to a track, I could race it normally after clearing the DTC, but after 10 minutes or so, the car showed "Power Reduced" in the screen and I had to pull over.
I don't see a connection (looking in the service manual) between this P2261 and the Power Reduced, and it didn't have any other trouble code stored...

I am not getting a fix from the official dealer, so I see this as an opportunity to start with the engine diagnostic/tuning myself, so I'm here to ask for advice in the following:
- Can this trouble code be generated by a previous tuning?
- Is the HP-tuners hardware and software capable of diagnosing, as well as tuning?
- What would I need to buy, for a start?

Thank you in advance!

[XploD]

Sorry, I tried editing but couldn't change the thread year.
It is a 2007 car, not a 2009.