B737-800
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Flight Crew Executed Go Around / Missed Approach
Aircraft
During approach and completing mechanical checklist crew became aware flap handle selected for flaps 30 but flap indicator showed flaps set at 25 and a green light. Captain ordered a go around and maintained configuration while I handled the radio and checklist. This event occurred after a long two leg all night flight and the conditions were nighttime windy and moderate turbulence at low altitude. We completed the checklist and returned to Runway XXL.  On short final we received a; 'TOO LOW FLAPS'; and 'TERRAIN TERRAIN' GPWS warning because I misread the non-normal checklist item calling for flap inhibit to be engaged. I attribute this misread to several factors. I was tired; this was a brutal trip assignment; it was turbulent and I was dividing my attention between the checklist and monitoring the aircraft status i.e. airspeed control radio and other set up functions.
B737 First Officer reported a flap malfunction on final approach.