Police attended a crash in Brighton Rd, Green Island, where a car had mounted the kerb about 8.55pm on Saturday.
The 17-year-old male driver recorded a breath alcohol level of 298 micrograms (mcg), on a zero-alcohol licence.
The incident has been referred to youth aid.
Senior Sergeant Anthony Bond, of Dunedin, said the vehicle had been sought by police following an incident earlier that day.
An occupant of the vehicle was believed to have presented what appeared to be a firearm at another member of the public in the Green Island area about 2.15pm, Snt Sgt Bond said.
The vehicle was searched in Brighton Rd and police found a plastic ‘‘cap gun’’.
"The investigation is still ongoing as to who presented the imitation firearm earlier that day," Snr Sgt Bond said.
Four people were believed to be in the vehicle when the imitation firearm was presented.
However, there were three occupants in the vehicle when it was found by police.
The occupants denied any knowledge of the incident, Snr Sgt Bond said.
