2014 F350 towed 3 times in the last month. goes to forced idle. first time message was count down to empty def even though it was full. they put a service bulletin in computer. went 30 miles and the message was forced idle soon. next ford dealer changed the nox sensor. went 50 miles and message was forced idle soon. towed in at the 3rd dealer and they are scratching their heads. any ideas other than trading it in for a Cummings? dave.