The main room shows a bed, couch, desk and a storage cupboard which doubles as a wardrobe.
Water, power and broadband were included in the rent.
The property was listed on Tuesday and had had 1117 views by noon yesterday before it was pulled by Ray White agent Serena Wan.
She told the Herald she had visited the house and taken photos but was in a hurry and didn't notice the unusual set-up initially/
Later she said she had asked Mr Wong to put up a partition to separate the two rooms.
"I shouldn't have done the advertisement first, I should have done the advertisement after," she said. "We didn't notice the function inside was not legal, so we are not listing it.
"We talked to the landlord, we can't list this kind of property. Some clients reported it wasn't legal."
Owner Anita Leung said she and her husband, who are from Hong Kong, did not know the room was illegal and would not be renting the flat. They had not rented it before.
"I don't want to rent the room because we can't do the kitchen in the bathroom ... it's illegal."
At least one door needs to be provided between the toilet and kitchen, according to the Building Code, said a spokeswoman for the Ministry of Business, Innovation and Employment.
The Residential Tenancies Act also states that the landlord must comply with all building and health and safety requirements.
An Auckland Council spokesman said the photos also suggested an additional unit had been created within the house without building consent which was a breach of the Building Act.
The council can prosecute under the act and impose a maximum fine for a breach of $200,000.
Tenants can complain to the Tenancy Tribunal, which can order landlords to pay the applicant up to $3000.
It can also make an order restraining the landlord from committing the same act again within a period of up to six years, a breach of which carries a fine of up to $2000.
Lyttelton Ave, Forrest Hill
• $190 a week.
• Studio flat attached to five-bedroom house.
• Kitchen, bathroom, laundry in one room.
• One car space.
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