I have 4 arrears in engineering including one detention. I am in the 2nd year of engineering. Is this going to affect my future?

This will not affect you, if you will clear them all in the 3rd year. Try not to bring any backlogs from 3rd year onwards. Some big companies might not allow you for the interview, but that is not a big issue because most of the companies will be allowing you if you are able to pass your B.Tech with