The alleged thief and his accomplice were confronted by the van's owner and involved in an altercation which left the owner and one of the alleged offenders in hospital.
The man was critically injured during the incident on Te Atatu Rd, in West Auckland at the weekend. He died today in hospital, police said.
"His death will be referred to the Coroner and police's thoughts are with his family," Detective Senior Sergeant Kim Libby, Waitemata CIB, said.
"At this stage, police are not in a position to confirm his identity.
"Enquiries are ongoing into this incident and police are still trying to locate a second man who left the address."
Police were called just after 4am on Sunday to a vehicle break-in on Te Atatu Rd, close to the northwestern motorway.
A police spokeswoman said at the time a person reported two men were breaking into his vehicle.
After an altercation the alleged thief and van owner were taken to hospital.
The injured man was taken to Auckland City Hospital, and police initially said he had a critical head injury. But they now say it's not clear why the man lost consciousness. The second alleged thief has not been found.
The owner of the van was taken to Waitākere Hospital in a moderate condition, but was discharged on Sunday.
