An elderly woman who accidentally left her car engine running in the garage died after being overcome by carbon monoxide fumes.
Grace Peggy Kitchingham, 88, was not wearing her hearing aids and probably didn't hear the engine running, a coroner has found.
Mrs Kitchingham was found by her daughter in the bathroom of her Christchurch flat on December 3, 2013.
She had driven home about 9pm the night before and parked in the garage.
After being alerted that Mrs Kitchingham had not drawn her blinds that morning, her daughter and son-in-law, Sandra and George Norquay, arrived at the unit and noticed a strong smell of engine fumes, and heat coming from the closed door to the internal garage.
Mr Norquay found the car running and the heater turned on.
Mrs Kitchingham's blood showed a carbon monoxide saturation of 60 per cent. A level of 50 per cent is generally considered fatal.
Pathologist Dr Martin Sage found it would not have been possible for the carbon monoxide to significantly penetrate the closed garage door.
A likely scenario was that Mrs Kitchingham left the door open and engine running, but woke in the night and shut the door, then collapsed on the bathroom floor.
She had poor hearing and was not wearing her hearing aids, so probably couldn't hear the car running.
Mrs Kitchingham also suffered from heart disease, which Coroner David Crerar said was a contributing factor to her death from accidental carbon monoxide poisoning.
There was no evidence the death was other than accidental, the Coroner said.