have a vokera boiler pressure ok but flashes 04 code gas board fitted new gas valve and flue but no joy then they fitted a diaphram but again no joy they suggested flushing system but its costly if it makes no difference could it be circuit board thats knocking it off the water pressure is at 1.5 bar so its fine

Lali, June 2012

Why did they fit a new gas valve and flue?
Sounds like the pressure sensor is at fault, yet another common Vokera problem. If you can find the sensor check it has good ohms reading with a multimeter, if id does then most likely the pcb.
Also the pressure vessel hose is prone to blocking with black sludge which can affect the senor value!

Bob, June 2012