The answer to this question is "I don't know." A lawyer in your area may be able answer this question, there are too many variables, the specific Judge who originally sentenced you, the Judge you may appear in front of if you violate your probation, the prosecutor who handled your case, the prosecutor who will handle the probation violation. Have you violated probation before? How recent was your second offense? How high was your blood alcohol concentration? Why did you violate your probation? These are some of the many considerations I have had to deal with in the 12+ years I have been exclusively handling DUI cases. I encourage you to hire an attorney to discuss the specific ramifications of failing to successfully complete your sentence.
Regardless of the jail time that you have hanging over your head you may find yourself unlicensed and unable to get licensed until you complete the DUI program. Again, that depends upon the facts specific to your situation, a lawyer can help you evaluate your path forward.
I basically agree with the first answer given. The answer depends upon too many variables to give a full and reasonable answer. It would be best if you asked your attorney who handled the last matter for you.
YOu should go to www.california-dui-lawyers.org to find a DUI lawyer in your area to get a free consultation. There are a lot of questions that need to be asked and answered before anyone can help you.