A police spokesperson said the northbound 'clip on' lanes were blocked for a time but had since been reopened although the speed limit on some lanes had been reduced.
Significant delays are expected and police encourage motorists to avoid the area if at all possible.
Traffic was backed up as far as Mt Wellington but was starting to flow again.
SH1 AUCKLAND HARBOUR BRIDGE - 3PM
A car fire is blocking lane two northbound (of 5) on the Harbour bridge. Police are on-site and emergency services are en route. Please expect delays and pass the incident with care. ^MF pic.twitter.com/WioAg4TtgD
— Waka Kotahi NZTA Auckland & Northland (@WakaKotahiAkNth) April 16, 2018
SH1 AUCKLAND HARBOUR BRIDGE - UPDATE 3.15PM The two northbound clip on lanes (lane 1 & 2 of 5) will remain CLOSED for sometime. Please use the three center northbound lanes and expect delays in the area. ^MF pic.twitter.com/LFj5cWScbE
— Waka Kotahi NZTA Auckland & Northland (@WakaKotahiAkNth) April 16, 2018