I own a Weber that once in a while does the saame thing except mine hangs around 300 degrees. Weber has a website that tells you how to correct the problem. Basically, turn off the gas at the bottle. Open all burners for at least 5 mins. Close all burners, open the gas back up and light you grill as you normally would. Works every time. A lot of frustration went into figuring that one out, let me tell you... Ha! Good Luck!