A Christchurch teen convicted for plotting a 2017 terror attack in the city has been warned by a judge that if he doesn't learn to control his temper, he faces a long stint in jail.

The boy, now aged 19, who cannot be named for legal reasons, was sentenced to intensive supervision at Christchurch District Court last February and has been regularly seeing a judge for judicial monitoring sessions.

He was radicalised online and had planned to ram a car into a group of people in Christchurch and then stab them. He told police that he'd "done it for Allah".

Last month, he admitted two breaches of the intensive supervision order by using his mother's phone to view pornography.

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At the court hearing, he said how the March 15 mosques terror attack had helped him reflect on his own earlier extremist thinking.

Today, he admitted a third unrelated breach – the details of which were suppressed by Judge Stephen O'Driscoll.

But the judge warned the teenager, who is living in supervised accommodation, that if he didn't control his anger and emotions, then he faced being sent to prison.

When he was initially sentenced last year, the Crown had been arguing for a five-year jail sentence. Judge O'Driscoll suggested the teen think about that the next time he gets angry or annoyed.

"Everyone is here trying to help and assist you," the judge told him today.

Other than the breaches, the teen had been making good progress, the court heard.

However, boredom has been a major issue. Corrections accepted that he needs to be getting out in the community and mixing with people of his own age.

He is now involved in weekly community projects, which he has enjoyed, says his lawyer Anselm Williams.

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Williams said a youth speciality services report had referred the boy to stopping violence services, which should be of benefit to him.

While there has been some negatives, the teen is continuing to make progress and is a different kid to the one of a year ago, Williams said.

After 51 Muslims were massacred in the March 15 mosque attacks, the teen earlier said he felt "disgust", not just for those who died and at how much it has affected the nation, but also disgust at thinking of the harm he himself could've done to "innocent Kiwis" who are "his people".

Last month, he said he felt sad and wanted to apologise to everyone for "having such views of hatred".

"All I can say is thank you to everyone who gave me a second chance," he told Judge O'Driscoll.

Rehabilitation had "pretty much saved my life" and helped "clear my mind from a lot of hatred".

Counselling is helping teach him methods to stop him feeling down or angry. He wants to participate in anxiety classes and an anger-management course.

On reflection, he can now see much progress he's made and wanted to tell the courtroom last month: "I will never go back to extremist thinking or ideologies. All it does is cause, grief, anger and sadness".