FORT WORTH, Texas — A judge on Wednesday ordered a Texas teenager who used an ‘‘affluenza’’ defense in a fatal drunken-driving wreck to serve nearly two years in jail, a surprising sanction that far exceeds the several months in jail that prosecutors initially said they would pursue.

Ethan Couch, who was appearing in adult court for the first time after he turned 19 on Monday, received 180 days for each of the four deaths in the June 2013 crash.

Initially, state District Judge Wayne Salvant said he would not immediately rule on how much longer Couch would spend in the Tarrant County jail. But he reconsidered after hearing an argument from prosecutors that Couch should be sentenced not to 120 days in jail for the crash, but to 180 days for each of four counts of intoxication manslaughter under a separate part of Texas code.

Couch had always faced the prospect of adult jail time as part of his probation once his case had moved out of the juvenile system. Prosecutors didn’t ask the judge to declare Couch had violated his juvenile probation by fleeing to Mexico with his mother last year, or to consider it in his ruling.

The initial sentence of 10 years of probation that Couch received in juvenile court outraged prosecutors and relatives of the victims, which include one teenager who was paralyzed.

The psychologist who suggested Couch had ‘‘affluenza’’ blamed Couch’s parents for having ‘‘taught him a system that’s 180 degrees from rational. If you hurt someone, say you’re sorry. In that family, if you hurt someone, send some money.’’

Associated Press