Thanks. Ye the newer manual uses E codes, the older (which applies to mine) uses P codes.

Ive spotted that the unit might need external 24V. I dont think this is the case with mine as it has a connector going back to the SZGH control panel where it has 24V available. That said, Ive asked them to see. If there is no 24V that might explain it too but not sure where I apply it as there are no power connectors apart from 2 spare solder points (3 - one is not tinned) in the cannon jack. That wire (the untinned one) does not have a partner on the plug, so I'm wondering if that might be where 24V is inserted. Doesnt sound practical, who knows ....