V

1. Check if lead disconnected from the safety temperature limiter.
2. Check the high limit of the safety temperature limiter and the harness for continuity.
3. Check the flow temperature to confirm actual temperature (may tripped out at lower temperature, leading to safety temperature limiter fault)
4. Check the system pressure and top up as required.
5. Check if air trapped in the system and in the boiler.
6. Pump seized/not running: check the pump for failure or if she blocked.
7. Check if blockage/restriction within boiler/pipe work restricting the flow.