Vaillant Fault Code F.53

F.53

Combustion regulation fault: The combustion regulation has detected a fault – Gas flow pressure too low – Liquid gas coding resistance used when operating with natural gas – If the fault occurs again after being cleared: – Gas valve defective – Mass flow sensor/Venturi defective, wet or blocked (if the fault occurs again after being cleared): Do not wet the sensor, do not use any lubricants on the O-ring on the Venturi.