Apple might recall its iPhone 6 Plus units to correct a functional defect that has led to some very unhappy customers.

Apple, the second largest smartphone vendor, might announce a recall for its iPhone 6 Plus units due to a faulty controller IC for the handset. The potential recall has nothing to do with the widely-reported bendgate or Antennagate. According to a report by Business Korea, the issue is limited to the 128GB version of the iPhone 6 Plus units that are fitted with a low-performance flash memory. Several owners of the high-end flagship smartphone reported functional errors, unexpected crashes or rebooting loops.

According to an early report by Apple Insider, replacing the malfunctioning handset also did not fix the issue and Apple's latest iOS 8.1 failed to address the problem. Apple hasn't publicly confirmed or addressed the rising issue but the industry analysts are expecting a potential recall to fix the hardware problem with the iPhone 6 Plus.

In a detailed note explaining the root of the problem, Business Korea said the TLC or triple-level cell NAND flash used in the iPhone 6 Plus is causing the problem. "It can store two to three times as much data as a single-level cell (SLC) that stores one bit of data and a multi-level cell (MLC) solid-state flash memory that stores two bits of data," the publication writes. "Moreover, TLC flash is more affordable. However, TLC is slower than SLC or MLC in reading and writing data."

A separate report from BGR found that TLC NAND flash was used in some iPads but Apple mainly opted for MLC NAND for its iPhones. It remains unclear why the tech giant chose the low-performance controller IC for its flagship high-end device. Issues related to TLC NAND memory were previously linked to some of Samsung SSD drives, including SSD 840 and 840 Evo. The Korean tech giant addressed the problem with firmware upgrades.

The problem is only with the 128GB version, the 16GB and 64GB haven't reported any such errors. Apple is revamping its inventory to meet the growing demand for its flagship smartphones. The company reportedly delayed the production of its biggest iPad in the wake of iPhone demand. It is highly important that Apple address the problem at the earliest to continue its great sales.