Firefighters from stations in Preston and Fulwood tackled the fire, which happened between the northbound junctions for Preston and Longridge. at around 7.10pm yesterday.
They used one water jet to douse the flames and left the scene after half an hour, the fire service said.
No injuries were reported.
Highways England, the Government-owned firm responsible for the nation's motorways, said the affected lane was re-open by 8.45pm, when the van was "safely awaiting recovery".
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