The collision occurred in Oxfordshire between junction 11 and the A422 at Banbury and junction 12 and the B4551 at Gaydon.
Two of three southbound lanes on the M40 briefly closed due to the collision, which involved a car coming to rest in a ditch.
Motorists should expect delays of 55 minutes due to the collision.
The collision has also caused four miles of congestion on the motorway.
Officials with Highways England encourage travellers to allow plenty of extra time for their journey this afternoon, Monday April 11.