Auckland viewers who get their television via an aerial lost reception to TVNZ 1, 2 and DUKE earlier this afternoon - and some will still be seeing a blank screen.
A fault at the Waiatarua transmission site caused an unscheduled outage at about 3.15pm, affecting all TVNZ channels in the Auckland region.
By 5pm TVNZ channels returned for some people, but one viewer in New Windsor said he still could not view channels belonging to the state-owned network.
TVNZ confirmed some people's signal would continue to be "patchy and unstable" this evening.
Work is continuing to fully restore the service as a matter of priority, TVNZ said.
Viewers can live stream TVNZ channels on TVNZ.co.nz. As a temporary measure, TVNZ 1 is now also available on Freeview channel 100.
TVNZ apologised to viewers for the inconvenience.
The fault has affected Auckland viewers who receive Freeview digital terrestrial signal TV.
Viewers who receive their TV via a satellite dish, such as Sky and Freeview DTH, are unaffected.