If you can get the heating on only by putting it into service mode indicates there is an issue with the boiler. Service mode only is for engineers when doing a service. However it is probably a cheap ish fix for an engineer. It could be a thermister inside the boiler that needs changing. Putting it into service mode often overrides these safety features...
I did it! You did it!! We did it!!! Thank you-thank you-thank you!!!
Sir, one last step is missing. I did something at the end last time and it worked, but can't remember now what that was... Cooooollllddddd...
If you can get the heating on only by putting it into service mode indicates there is an issue with the boiler. Service mode only is for engineers when doing a service. However it is probably a cheap ish fix for an engineer. It could be a thermister inside the boiler that needs changing. Putting it into service mode often overrides these safety features...