Went to P.O. 3 times missed one date because of car trouble called P.O. said OK be there next month went to two probation dates , on the last date he went in they arrested him for non response probation. What can happen.

What can happen [?]

His probation can be revoked, and it is possible that he will spend the rest of his sentence in jail.

Make sure he has a criminal-law attorney onboard.

He can be sent back to prison to serve the prison time. Sounds like there is more than just missing one appointment.

Car troubles aren't an excuse. If you are to be at your meeting, you find a way to get there.