I would have thought if the continuity checks out on the gas valve, the engineer then tested the pcb? Our two-man teams can attend your premises to deal with emergencies rapidly, and we're on call hours a day, days a year. What does it do? should you switch your boiler to eco-mode? is it cheaper to fun than the standard setting? Have a year old combi in our three story house, no issues with running baths and showers. We ensure that our products are installed.