More than 20,000 motorists have so far ignored calls to get their vehicle's warrants rechecked despite warnings of faulty tests from the New Zealand Transport Agency.
Late last year, more than a dozen inspectors or garages that issue warrants were suspended for issuing dodgy certifications.
Almost 25,000 motorists were asked to get their vehicles rechecked.
As of 9 January, just over 4000 vehicles had been reinspected. Sixty percent of those vehicles failed their first re-inspection.
Despite one or more re-checks, there are still almost 700 vehicles which have not passed.
The inspector with the highest re-check fail rate was Aaron Grant at Te Aroha Automotive.
Seventy-seven percent of vehicles with warrants from the inspector failed their first re-check - or 68 out of 88 vehicles.
Meredith Connell Managing Partner Steve Haszard, who is leading the Transport Agency's compliance work, is urging people to get their vehicles re-checked.
"We can't legally compel vehicle owners to get their vehicles rechecked, but it's important that the owners of these vehicles understand that they may not have been properly inspected during the previous WoF check carried out by these suspended providers," Mr Haszard said.
All vehicle owners have a responsibility to ensure their vehicle's warrant is up to standard every day it is on the road, Mr Haszard said.
NZTA is covering the costs of re-inspection and has been contacting affected owners in writing and by phone.
By the numbers
Vehicles affected: 24,803
Vehicles reinspected: 4070
Vehicles with a passed reinspection: 3382
Vehicles passed first reinspection: 1608
Vehicles failed first reinspection: 2462
First time re-inspection pass rate: 40 percent
Overall reinspection pass rate: 83 percent