A West Auckland mother has admitted driving under the influence of methamphetamine and causing a crash that killed her daughter.

Toni Ericksen, 33, was due to stand trial in the Auckland District Court on Monday on four charges including driving under the influence of drugs and being while prohibited, but last week entered a guilty plea.

Her daughter Bryer Greenwood, 12, was killed when the car Ericksen was driving crashed in Kaipara on July 9, last year.

Her younger daughter Gemma was also injured, along with the heavily pregnant driver of another vehicle.

Ericksen, who was an unlicensed driver, and her two daughters were heading home from a netball game when the car they were in collided with another vehicle on the Kaipara Coast Highway, 2km north of Helensville.

All three had to be cut from the wreckage of their car, which was "T-boned" by an oncoming 4WD, emergency services said at the time.

At her funeral in July, Greenwood was described as an intelligent, beautiful and vivacious girl.

Family said the Kaukapakapa schoolgirl had her whole life planned out.

She wanted to go to Orewa College and then on to the University of Otago where she wanted to become a professor in archaeology. She and a friend had planned to visit Machu Picchu in Peru and other areas throughout the world.

Ericksen will be sentenced on November 30.

- © Fairfax NZ News