By design, Apple’s iOS 9 can disable an iPhone 6 when it detects a Touch ID sensor that was not originally installed on the device by Apple technicians. Reuters/Yuya Shino

Apple is facing a class-action lawsuit over an iOS software update that can render iPhones useless if the screen is repaired by a vendor not approved by the company.

The update, part of Apple’s iOS 9, is intended to protect data secured by the iPhone 6's Touch ID sensor, which became a more serious issue with the introduction of Apple Pay.

When an unauthorized screen is installed, the device may display a message known as “error 53.” In addition to the error, the iPhone is then rendered inoperable — a process known as bricking. Users affected by the error are then left with purchasing a replacement device, since repairs performed by non-Apple technicians rendered the warranty invalid.

The lawsuit, filed in federal court in San Francisco by Seattle law firm Pfau Cochran Vertetis Amala, alleges Apple went too far with its control over the iPhone and took no steps to warn customers that updating to iOS 9 could disable their phones and cause data loss.

“The first objective is to get all the affected iPhone customers reoutfitted with working phones, and without the overwhelming costs that thousands of people are facing right now with error 53 codes and bricked phones,” Darrell Cochran, lead attorney for the class action suit, said in a press statement. “That will provide immediate relief to the consumers and, in the end, it will also help Apple.”

The suit seeks at least $5 million in damages for its affected clients, replacement devices and a software update that removes the error from iOS.

The iPhone maker told the Guardian last Friday the error is part of the iPhone's security features designed to protect fingerprint data and other sensitive information, such as the Apple Pay mobile payment information stored in the part of the iPhone’s processor called the Secure Enclave. Apple documents some of its security features in an extensive 60-page white paper available online.