what can i do
If it is the E1 error, it is most likely the sensor cord that runs from the back of the smoke generator to the tower. Try plugging and unplugging both ends a few times in order to make a good connection.
Here is a link to many troubleshooting tips:
Bradley FAQ's (http://www.susanminor.org/forums/showthread.php?481-Bradley-Smoker-FAQ-s&p=748#post748)