So 3 times now i have had this issue with my boiler turning the burner off because it senses an error on the flow/return temp sensor. Had ideal round to check it out, no faults found they changed the sensor anyway and left me a spare then monitored the system for a while and noted that occasionally the boiler would read the return temp higher than the flow and that with the system set to off the boiler then fired up again a few minutes later (he was unfamiliar with Evohome, and i know when you set the heating to off it can take a number of minutes to actually fully switch all zones off). He did suggest opening the auto-bypass more but otherwise said the boiler is working fine. On thinking about when it seems to do this, i'm wondering if its when Evohome has so little demand for example one radiator on the lowest setting, the auto-bypass is flowing the majority of the water and as this circuit is so short and no where for any heat to go this causes the issue. But could it also be not open enough and when the water suddenly has no where to go it senses a spike in return temp. Anyway to figure out exactly whats causing this or should i just open the valve another 2 settings? This is the specific fault. Pressing Restart gets things working again. Any advice would be appreciated. I do actually have a photo of the valve and you can see its set between 0.2 and 0.3.