Gulfstream G200 (IAI 1126 Galaxy)
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Aircraft Equipment Problem Less Severe
Flight Crew Diverted
Equipment / Tooling; Aircraft
We started our preparation for a flight by pre-flying the aircraft in accordance to the SOP's and checklist with no visual abnormalities. We then proceeded to taxi for takeoff following the checklist and SOP's; at that time no messages on our computer were displayed. So we continued; just before takeoff we checked our computer one more time for no messages; after rotation and departure the computer still had no messages until we reached 4;000 ft. MSL. After we reached 4;000 ft. MSL the computer gave us a message of 'CABIN DOOR'. As soon as we received indication we immediately initiated checklist. At that point we realize the pressurization was abnormal. We attempted to troubleshoot the problem by proceeding with the SOP's and by a checklist and visual inspection; however; the checklist indicated to land as soon as possible so we proceeded to divert to ZZZ1 since we were too heavy to land back at ZZZ. Other than the abnormal pressurization indication no other issues presented itself on our way to ZZZ1 and we landed with no further incidents.
A G200 First Officer reported a 'Cabin Door' warning and abnormal pressurization on climbout; resulting in a diversion.