Fault Code: P2004 - Help!

[The Beanster]

During my last track event, I thought my car was lacking a bit of power. Maybe, maybe not. But when I checked with my Durametric cable, I got this error.  
Bosch Digital Motor Electronics Motronic 7.8.1 Turbo

Current Fault Codes    
P2004: Catalyst system efficiency below threshold bank 1
Value below lower limit value
 

It appears it could be something with the pre or post cat O2 sensor. 

Any one seen this issue and fixed it? And which side is bank 1?

[JFP in PA]

During my last track event, I thought my car was lacking a bit of power. Maybe, maybe not. But when I checked with my Durametric cable, I got this error.  

Bosch Digital Motor Electronics Motronic 7.8.1 Turbo

Current Fault Codes    

P2004: Catalyst system efficiency below threshold bank 1

Value below lower limit value

 

It appears it could be something with the pre or post cat O2 sensor. 

Any one seen this issue and fixed it? And which side is bank 1?

 

 

I would be concerned about the cat it self considering your comment about the track.  At this juncture, I would be looking at the performance of the pre and post cat O2 sensors, looking for how they cycle (or fail to).  You could have a cat going out, or a bad O2 sensor, you need to diagnose which one is the correct issue before spending a lot of money.  The following charts are for a Boxster, but the operational theory is the same for your Turbo:

 

 

[Silver_TT]

JFP is giving good advice as usual.  Use your Durametric to log the precat and postcat sensors and you can chart the data (or see it live in Durametric) to compare it against the charts he provided.  I had the same issue on a Carrera 4S and the cat was bad.