You can rely our which? trusted trader certified staff we have years experience installing and repairing boilers from all the top manufacturers. Use a plunger, snake, wire hangar, or snare (snares are my personal favorite.). According the baxi’s own list of error codes, the 118 fault is directly related to low water pressure in the boiler. A plumber is someone who maintains water piping and drainage systems in the home and in industry for a variety of.