The Remutaka Hill Rd was closed Sunday afternoon after a car fire spread to surrounding bush on the Featherston side.
The road was closed from 12.10pm but was reopened shortly after 3.30pm under stop and go control.
Road users are advised to expect delays and allow for extra travel time on their journey.
A Fire and Emergency spokesperson said the blaze had been contained to a 500 square metre patch and around 30 crew were on the ground.
A helicopter and water tanker had also been brought in to put out the fire.