McLeod pleaded guilty to undertaking an unauthorised gas fitting, failing to take all practicable steps to ensure that gas appliances were safe and completing gas work where not authorised to do so.
The charges were brought by Energy Safety, part of WorkSafe NZ, and carry a maximum penalty of two years in prison or a $100,000 fine.
McLeod, a registered drainlayer, had personally installed the gas cooker - work that by law has to be done by a licensed gasfitter.
Energy Safety manager Mark Wogan said Ms Wehi-Jack's death was completely avoidable and a tragic waste of a young life.
"When Lesley rented the house, she had every right to assume that it was safe to live in.
"If Mr McLeod had followed the law and got a qualified gasfitter in to install the cooker she would probably still be alive today. It is that simple," Mr Wogan said. "The consequences of risk-taking with gas and electricity can be catastrophic. Doing the work yourself, or on the cheap, is simply not worth it."
He said McLeod must live with the consequences of his actions.
In court Miss Wehi-Jack's uncle, Dion Stone, read his victim impact statement to the court and told McLeod it was hard for the family not to be angry with him.
"You took our loved one from us.
"She was our taonga, she was a gift, she was our precious person that you have taken away," he told McLeod, who sat in the dock with his head bowed.
Members of her family including a brother and sister filled the public gallery and sang a song to complete their part in sentencing.
In a probation report, a remorseful McLeod had said he accepted responsibility for Miss Wehi-Jack's death.
"I think about this poor little girl each night".
Judge Keith de Ridder said in the mid-90s, McLeod had built the house and installed the gas himself. The house was moved on to another section and the gas installations remained.
Mcleod had lived in the house with his wife until 2011 when he went to Christchurch to help with the rebuild.
The house was then rented but, before tenants moved in, McLeod removed the cooker, had it checked then reinstalled it himself.