The traffic has been stopped on the northbound from J32 near Blackpool and Fleetwood until J33, near Lancaster.
Drivers are advised to take care as they approach.
Fire services rushed to the scene to assist.
National Highways said in an announcement on Twitter: “Traffic has been stopped on the #M6 northbound between J32 #Blackpool #Fleetwood and J33 #Lancaster #A6 near @motoway #LancasterServices.
“@LancashireFRS are on scene with a vehicle fire. Delays are building on the approach, please take care. Updates to follow.”