Scirocco Central

First of all I hope I posted in the right place.

Second of all, I've noticed that my 2009 Scirocco 1.4TSI revs to about 1100 rpm when starting the engine then drops to normal rpm (about 800) after 30 seconds and everything runs good. The engine sound and exhaust sound are different compared to when I rev her up to 1100 rpm, it's more deep. I've noticed this last winter when I bought her but back then it occured rarely. Now in summer it occurs every day after the car sat for 24 hours, even though the temperature outside is 30 degrees celsius. I have check engine on with P0420 code (Catalyst System Efficiency Below Threshold). Should I be worried? Thank you in advance.

Sounds perfectly normal therefore I wouldn't be worried. Under certain conditions on start up the engine runs slightly different fueling / timing for emissions to heat the cats up quicker hence the different sound and higher revs for a short period.

On some other engines they have a Secondary Air Injection (SAI) system that performs a similar function.

Have a read of "Blower"'s post on this thread;
http://www.sciroccocentral.co.uk/forum/ ... on#p208011" onclick="window.open(this.href);return false;

Thank you so much! Also I was worried about white smoke, wanted to make another topic, you saved me!