Potterton Suprima HE "air pressure signal" problem

[Ezzo]

This morning the boiler did not come on and the fault was apparently due to an "air pressure signal" problem according to the lighting on the front panel.
I have followed the intructions and turned it off and re-started the boiler. It does re-start but then goes off again after a while.
Could it be due to the outside vent where the steam is releeased, becoming frozen over-night?
Any advice gratefully received.
Ezzo

 

[Baxi-Remeha]

more than likly a frozen condensate pipe. look for a plastic pipe going through the wall to outside. try pouring hot/boiling water over it to defrost it..