worcester 24i junior red light flashing 1 every second?

hi
i have read up on this from loads of post, posable water pressure switch faulty. My boiler when turned on tries to fire up then red reset light flashes every second. also the bar gage seems to be faulty as i drained the system with the pressure release vaulve and gauge still showed 0.5 bar when empty,then re filled to 1.5 bar which it did really quick.
Could this be the water pressure switch being faulty and showing wrong pressure in system.