I have a fault code come up on a display of E3 which says it could be

High Pressure
Defect of high pressure switch
Defect of outdoor unit main Pc board A1P
Instantaneous power failure
Faulty high pressure sensor

Where the best place to check first as all the zone areas are coming up faults also where I live the Daikin back up is terrible
Or does any one have info on these units this is 10 years old