Your code will be 03 because you completed your PUC from Karnataka. Code 03 says: The Intermediate/Pre-degree Examination in Science of an Indian University/Board or other recognised examining body with Physics, Chemistry, Biology /Biotechnology (which shall include practical test in these subjects) and also English as a compulsory subject.

But if you have already utilised the correction window once, you cannot use it again. While this will not cause any issues during the State Counselling, please write to NEET helpdesk at their official email id: neetug-nta@nic.in