I have a Vokera Linea combination boiler. It's been working fine then suddenly flashed 04 error (low pressure) The pressure gauge is down to 0. When I turn the fill knob I can't hear water. I have checked for leaks around the flat but no obvious evidence. I have bled a couple of radiators but there doesn't seem to be any sign of air.
Can anyone tell me why this has suddenly happened and what else I can try before I call out an engineer.
Many thanks

Sally C, May 2009

you will probaly find that your expansion vessel is low on air and the system has blown your prv valve you will need a engineer to repair this

liz, May 2009