You didn't say which B&G system you have, but assuming it's in their Hydra series, you can try resetting the Depth board.

I don't remember exactly how you do this, but it's something like the following: go into diagnostics mode (power-up and lights key pressed simultaneously), then select "Reset System", then select the Depth board (which I believe is what the temperature sensor is on).

You'll have to re-enter calibration information, so make sure you note it before you do the reset.

-tk