In the export version of Type 212 submarines, the 214s suffer from various problems. According to political sources from the ROK who prepared reports, some major defects were detected on all nine Son Won-il Class submarines. Boats are modified versions of the German Type 214 vessels, also known as KSS II.

Some problems detected in the inverter module cabling were found on seven Son Won-il class submarines. Two of them were announced as functional defects. The modules were procured from Germany. Systems are produced by Siemens, which are critical components for propulsion infrastructure as they are the heart of the Air Independent Propulsion (AIP) system. Each boat has twelve of them. According to open sources, three Son Won-il vessels suffered from problems due to a known method. There are some predictions, but the cause of the defect is still officially unknown. Seven subs are deployed without necessary repairs, which risks vessels and the entire crew.

The ROK paid around USD 5 million for repairs. But the production, transportation from Germany to Korea and installation of the components take around six months. It is known that the long process negatively affects the combat readiness of the entire fleet.

Hellenic Navy also experienced many problems with the Type 214 submarine. The biggest issue was the instability. Excessive propeller cavitation, overheating in the fuel cells of the Air Independent Propulsion system and excessive listing in lousy weather when surfaced. Greece detected additional issues such as insufficient AIP output power and efficiency, high periscope vibration, sonar flank array problems and seawater leakage into the hydraulic infrastructure of the vessel and rejected the first hull of the programme, named “Papanikolis”. It is known that the Hellenic Navy has excessive readiness rate problems with Type 214 submarines and cannot deploy efficiently.

Turkish Navy is also building its own Type 214 submarines under license and cooperation with German partners. They are called Reis Class. Turkiye did not accept the adding weights to specific compartments of vessel solution, which TKMS developed for Hellenic Navy boats, and came up with a unique solution. Turkish Navy, which conducts studies on submarine technology and associated problems, extended the length of the boat and relocated the position of the centre of gravity to bring stability. Reis class submarines have the same AIP technology.