My oil fired Rangemaster/Brandon has frequently come up with a code 04, easily reset. It may happen first thing in the morning or at any time of day. Aga suggested "Boiler high limit switch opened, no service kit available" but did not offer any solution. It has not happened for the past ten days (!) but I do not trust it. Has anyone met this problem before? There does not seem to be any sort of service manual available.
