Northants Police's Road Crime Team have warned motorists of delays in the area until the carriageway fully reopens.
National Highways has advised drivers that in addition to lane one the entry slip road at Junction 11 onto the A14 westbound at Twywell is closed whilst the carriageway is inspected for damage and for recovery.
In a tweet at Northants Road Crime Team said: "Our crews are on scene at this lorry fire. This is expected to be the case for at least another 45 minutes. A diversion is in place, and please avoid this route if you can."
Tailbacks have reached the Islip (A6116) turn (junction 12) all they way from junction 11 - the turn for Finedon (A510).