Three crews rushed to the scene on the eastbound carriageway between Preston and Cluddley in Wellington at about 7.20pm yesterday.
A fire had broken out in a heavy goods vehicle involving the exhaust system and mud guards.
A defective turbo was blamed.
Police were also at the scene.
Firefighters also tackled a small fire involving two domestic wheelie bins in Bishopdale, Brookside, at about 7.50pm yesterday.