Sydney mum accused of leaving child in car

A woman will face court in December after allegedly leaving her two-year-old son in a car to attend an auction on Sydney's northern beaches.

A Sydney mother has been accused of leaving her toddler alone in a parked car so she could attend a house auction up the street.

NSW Police say beachgoers at Freshwater spotted the two-year-old sleeping in a black four-wheel drive on Saturday morning.

A surf lifesaver opened the car doors to get some fresh air into the vehicle while another passer-by called for help.

The little boy woke up during the commotion but did not appear to be injured, police say.

When Northern Beaches Local Area Command officers arrived and began a search for the child's parents they didn't have to look far - both mum and dad were allegedly at a house auction about 300 metres away.

The child's mother, 40, has been ordered to appear at Manly Local Court on December 16 to answer a charge of leaving a child unattended in a motor vehicle, causing emotional distress.

The child's father has not been charged.

And it seems the couple didn't secure a home for their trouble - Ray White real estate agent Ken Snell has told AAP the three-bedroom weatherboard home went to a local family.