"It's a matter of time that someone gets killed, whether it's a firefighter or a member of the public," said northern branch secretary Boyd Raines.
He said the faults were widespread across the fleet of vehicles, introduced just last year, and were preventing firefighters from doing their job. So far there had been 215 complaints of gear failure.
"When a door flies open when you're responding to a call it's a little bit disconcerting. When you can't get out of your truck to do your firefighting duties or do medical duties or CPR that's quite disconcerting for the firefighters. Or a pump won't go into gear at a fire so you can't put the fire out or do search and rescue if there are people trapped."
But New Zealand Fire Service Auckland regional manager Kerry Gregory said the engines were not posing a dire threat but experiencing "teething problems".
"Our firefighters expect everything to be of the highest standard. They put their lives at risk for the public and expect it to be 100 percent. I really understand the frustration of our troops on the frontline and we're moving to fix the issues."
He said the fire trucks were state-of-the-art and problems were being addressed as they arose. So far this included replacement throttles and back door latches.
He said the move to boycott a critical vehicle in the central city fleet was displaying a "sense of frustration" than it being a matter of life or death.
"There's no way we would have a vehicle on active duty if there was a problem to risk of public and firefighters," said Gregory.
Boyd said at a house fire in central Auckland this week, one fire engine could not get water pumping through a hose and a second broke down at the station.
It's the first time in 20 years that firefighters have been forced to blacklist a fire engine because of safety concerns.
Raines said the union considered the risk to firefighters and the public was "too high".
He said the action was effective immediately.
Internal Affairs Minister Peter Dunne, who's responsible for our National Fire Service, isn't prepared to comment on claims more than a dozen new fire engines are faulty.
Dunne said he hasn't been briefed on the matter, and referred all enquiries to the National Commander of the Fire Service.
NZ First Internal Affairs spokesman Clayton Mitchell said Dunne wasn't on top of his portfolio. He understood in the last 18 months more than 12 Auckland fire trucks had 215 faults reported.
"The fact is firefighters and the public's lives are being put at risk because if inadequate Government funding."
