How do I solve the fault codes e33/34 on my ariston microgenus 28kw condensing boiler? I have changed the air pressure switch and cleaned all the silicone hoses from the switch to the fan. I've even removed the fan to check for blockages to the switch and had no joy!! Any suggestions please on what else it could be.

Phil, July 2008

Did you ever manage to fix the problem. I have been told that this problem usually relates to a faulty flue

cliftonsmith@vodafone.net, November 2008