This says error code 6 is E6: Over Temperature.
Outlet Water Temperature has exceeded 60°C for 3 sec
E6: Over Temperature.
Outlet Water Temperature has exceeded 140°F (60°C) for 3 sec.
The main cause of overheating in this water heater is purging all of the air out of the plumbing and high temperature cold
water coming into the water heater. Southern states in the summer time can get extremely warm water right out of the
ground. When these conditions occur ensure that your water flow is proper.