The car does not start. DTC B144C 06, B2515 5A, many U-xxxx codes or many codes for low voltage
New 9-5 (650)
DTC B2515 5A or B144C 06, many U-xxxx codes or many codes for low voltage (Check this even if these codes are not set)
Check the clamping force for the starter relay (position 2 in UEC), main relay (position 15 in UEC) and engine relay (position 7 in UEC). There shall be clearly visible marks on both sides of each pin. If not sufficient adjust in UEC.
Check also all connectors for the UEC. Sometimes it could be enough to just disconnect/connect.
Check the ground point for UEC. It is located on the radiator member.
Check that the big fuses (100A -300A) are mounted properly (tighten the screws/nuts). There shall not be any voltage drop over each fuse.