Changing your caste category from General to OBC in the second year of engineering is possible, but it depends on your college's policies and procedures.

To make this change, you'll typically need to:

- Obtain a Caste Certificate: Get a valid OBC caste certificate from the SDM office in your area.

- Submit an Affidavit: Attach an affidavit stating that you've just obtained the caste certificate.

- Contact Your College: Reach out to your college administration to inquire about their process for updating your caste category.

However, not all colleges may accept this change, and some might have specific rules or deadlines for submitting caste certificates.it's essential to check with your college to confirm their policies.

Regarding the reduction of fees, it's also dependent on your college's rules and regulations. Some colleges might offer a fee concession or waiver for OBC students, but this varies from institution to institution.