Vokera Linea 24 Error Code 01?

Hi

Boiler locked out and showed error code of 04 , got guy out who repressureised boilier and replaced pump at cost of £100 , 2 days later boiler chucks it again and now its shows error code of 01 whith red light flashing , when try to reset boilier iginites for about 3 seconds then cuts out and goes back to 01 , water pressure is sitting about 1.5 bar , any ideas ?

thanks John