Driving and vehicle testing officials at Vehicle Testing New Zealand will walk off the job today, now that mediation has failed to resolve a pay dispute with their employer.
E tū union members, who say they are not paid enough for a hazardous and dangerous job, will strike for 24 hours.
Since 2014, VTNZ has been run by a German company, Dekra, which members say has refused to increase wages.
Union advocate Sunny Sehgal says workers often face threatening customers and it's not uncommon to have to call the police.
He says the vehicle testing station mechanics are paid just over $20/hr, which is well below the industry standard.
VTNZ was a state-owned enterprise before being privatised in 1999. It's been appointed by the Transport Agency to carry out vehicle inspections, and contracted to provide vehicle registration and driver licensing services.