Traffic was stopped on the eastbound carriageway between Junction 9 and Junction 10 this morning, with long delays forming.
It was partially re-opened as emergency services kept lane one closed before fully re-opening at about 1.15pm.
A Northamptonshire Fire & Rescue Service spokesman said: “Fire control received a call at 10.30am reporting a vehicle fire on A14 eastbound between Junctions 9 and 10. On arrival, crews from Kettering and Burton Latimer found a vehicle fully alight.
"Two firefighters wearing breathing apparatus used a hose reel jet, a 45mm jet, small gear and foam to bring the fire under control and put out the flames. “ The eastbound carriageway was closed whilst firefighters worked to extinguish the fire and make the vehicle safe."
The spokesman added that the occupants were left with the Highways agency who were at the scene.