Are you running on gas or electric?
I only run on electric and have had this fault on a few occations when there is a high wind, or the wind is blowing in the "wrong" direction ie up the exhaust pipe.
I have a work around to place my aquaroll near the exhaust to shelter it from the wind. Turn off everything at master switch and restart everything.
It's yet another reason why my next caravan won't have a whale i-van system
NB, don't block or obstruct the exhaust if you are running on Gas!!