The road was closed between the Carholme and Skellingthorpe roundabouts after a car fire on Tuesday afternoon.
At least two fire engines attended the scene and photos show crews putting out the fire of the badly damaged car.
Fortunately nobody was injured in the fire, but the incident has caused traffic to build up in the area.
Lincolnshire Police said: “We were called to the scene of a vehicle on fire in the road on the A46, southbound from the Carholme roundabout heading towards the Skellingthorpe roundabout, at 2.47pm on 28 June (incident 224).
“The fire service are currently on scene and recovery vehicles are on their way. One lane is closed southbound; the outer lane remains open but the traffic is slow moving. There are not thought to be any injuries at the scene.”
A spokesperson for Lincolnshire Fire & Rescue confirmed the fire was caused by a fault within the engine compartment.
They said: “Lincolnshire Fire and Rescue were called out at 2:46m on June 28 to the Lincoln bypass near Carholme roundabout. Saxilby and Lincoln North crews attended to extinguish the fire involving one Triumph TR6, using two breathing apparatus and two hose reels.”