The other driver, Mrs Leitch, died at the scene and her husband suffered a broken knee.
"When spoken to by police [Chen] was unable to explain how his car crossed the centre line of the highway," the judge said.
Defence lawyer Jamie Waugh called it a momentary lapse of attention: "He's been driving in New Zealand for years without incident. He is genuinelyremorseful."
Mr Waugh said Chen had attended a restorativejustice conference which had been successful.
Judge Cameron said Mrs Leitch's husband suffered immense ongoing grief but had forgiven Chen: "(The family) do not want the defendant sent to jail for this offending.
"I need to hold Mr Chen accountable for his actions."
Chen was sentenced to pay $5000 emotional-harm reparation and was disqualified from driving for two years.
He was remanded at large to reappear on September 21 for the court to check if the payment had been made. Chen will be re-sentenced if it has not.