The driver pulled onto the hard shoulder at junction 11 having realised something was wrong and found a small fire underneath the vehicle at around 9am.
The coach party, which included 44 children and four teachers from Northfield Academy in Birmingham, evacuated and waited on the grass verge by the roundabout while a replacement bus was sent.
Three fire engines from Banbury and Deddington arrived at 9.15am along with police – the fire was extinguished while one lane of the southbound carriageway was closed.
A fire service spokesman said a safe ‘footpath’ was created to allow the children and teachers to walk to the replacement vehicle from Swan Street Coaches, staying clear of the operational carriageway.
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No injuries were reported and the motorway is now fully open.