It is Ariston microGENUS HE 28 MFFI combi condensate boiler.
Ones it is heat up it shuts down, even if hot water is open. It's resets alright, but the same error occurs again.

Gintaras, January 2006

I had the same problem. I managed to get the boiler running by removing the air pressure switch and locating it to the side of the boiler. Then I directly connected the output from the fan to the switch instead of going via the plastic manifold. I suspended the switch so that it is kept level & the boiler stays running. I'm waiting on a new switch which will hopefully resolve the problem.

jvr, March 2008

The problem is with the air pressure sensor switch. Check that the small hoses going to the sensor are OK and electrical connections are good. If all is well then you may need a new pressure switch. Switches are readily available from spare part stockists and should not cost much more than £30. The manual should show where this switch is located.

Grant, February 2006