Flight MH198 left Kuala Lumpur at 10:20 p.m. (1220 GMT) on Thursday and returned at 2:10 a.m., with all passengers and crew safe.
"The defect did not have any impact on the safety of the aircraft or passengers, however as a precautionary measure, the operating captain decided to turn back," said MAS.
The loss-making airline has had a difficult year. Flight MH370 disappeared in March and Flight MH17 was shot down over Ukraine in July.
Last month, MAS said it would slash nearly a third of its 20,000 workforce and cut back its global route network as part of a radical 6 billion ringgit ($1.9 billion) restructuring following the devastating impact of the two jetliner disasters. REUTERS