My sister has a no bail warrant she was sentenced and walked out of courthouse.does the warrant stay active until she is arrested and sees the judge again.

The warrant will stay active forever until she is arrested, I doubt she will go before the judge again, most likely just to go to their sentence ( if they were to go to jail, then they will most likely be sent to serve their sentence

Most likely she will have a bench warrant put out for her. Meaning they won't actively search for her, but if she happens to be pulled over for a traffic offense, or the cops are called to her house for a domestic incident, etc. they will arrest her and take her to jail.

If she was sentenced to serve jail time they could also charge her with Failure to Report to
Jail.

Also if she was sentenced to probation, her PO would also put a warrant out and put her on a hold.