Results of the inspections, from April 16 this year to May 9, were published on the NZTA website after a request was made by a member of the public under the Official Information Act.
The NZTA today said the follow-up checks are to ensure the safety of the travelling public.
"Bus companies have the ultimate responsibility to ensure their vehicles remain in a roadworthy and safe condition at all times, and police and the Transport Agency will be following up over the next 48 hours to ensure this is the case," said Kate Styles, NZTA regional manager for access and use.
"Police and ... road safety partner agencies have been working closely with bus operators, including New Zealand Bus which runs most of the services in the Wellington region, to ensure they understand what is required of them if they want to continue to operate.
"They in turn have given assurances that the serious problems identified earlier in year have been rectified and police Commercial Vehicle Investigation Unit (CVIU) and Transport Agency inspectors will be checking to make sure this has happened."
Senior Sergeant Willie Roy of the CVIU said it was hoped there would be as little disruption as possible to normal bus services - but it would ultimately depend on the action taken by the operators to fix the problems previously identified.
"To ensure as little disruption to the public as possible, the operation is being run outside of peak hours, targeting buses not carrying passengers," he said.
"However, bus operators should be on notice that if serious safety faults are detected, then action will be taken, as ensuring public safety is our top priority."
Mr Roy said inspectors would be carrying out the spot checks of buses throughout the region today and tomorrow to ensure compliance - with a particular focus on fumes, fire hazards and emergency exits.
