When you're put on probation following a DUI conviction, you'll be expected to pay any fines and penalties required by statute. You'll also be expected to complete alcohol-education and driver-retraining classes. Finally, you'll need to observe a mandatory license suspension period. If you're able to do all of these things, you'll likely avoid jail time and should be able to resume normal living once your probation period has ended.
In most jurisdictions, violating any of the terms of probation is a serious crime. If you currently live in the state in which you committed the original offense, you'll be subject to arrest on your outstanding warrant. While it's unlikely that the local authorities will initiate a manhunt to bring you to justice for a DUI-related probation violation, they may come looking for you at your last known residence or place of employment. It's more likely that you'll eventually slip up and commit a minor vehicular infraction that draws the attention of the police. After all, outstanding arrest warrants are readily available in the computerized filing system that traffic cops use to check for prior moving violations.
Once you're back in custody, you'll be required to complete any unfulfilled or suspended elements of your original DUI conviction. This may mean that you'll have to spend some time in jail and pay some additional fines. If you miss a court appearance related to your probation violation and evade the authorities thereafter, you may open yourself to a "failure to appear" charge that typically carries its own set of fines as well as a short but mandatory prison sentence.
If you're currently living outside of the state in which you committed your original crime, the local authorities are unlikely to execute the arrest warrant for your probation violation. This doesn't mean that you can hide from the law forever: Since outstanding arrest warrants can be accessed through a national law enforcement database, you'll be subject to extradition proceedings after a local traffic stop or minor-crime arrest. You may eventually face stiff penalties in your former home state.
To reduce the severity of these consequences, turn yourself in to the local authorities as soon as you learn of the warrant and contact a local lawyer. In some cases, you may be able to escape a reinstated prison sentence by paying a hefty series of fines to the authorities back home.