question for warrior 9920

[Ozark-al]

I am sure this has been posted somewhere before so I'm sorry for the repeat. My 9920 runs great but after a short time maybe 4-5 minutes, the motor will stop running and the servo for the steering gets stuck when turning. The truck still seems to have the max power in the batts, but it seems like it goes in to a safety mode and won't allow the motor to engage. Is this a problem with the internal BEC of the 9920? Can this pro blem be solved with the installation of a UBEC? Thanks for any help.