A technical issue that dates back to 2012 continues to haunt Tesla and now the US government is getting involved. Last November, the California-based automaker acknowledged there are serious technical issues involving the Media Control Unit (MCU) touchscreen on the 2012 to 2015 Tesla Model S and Model X. In, short a number of touchscreens began to fail, rendering vehicles almost completely useless. Without working screens, drivers cannot control a variety of basic functions.

Complicating matters further for owners was that Tesla claimed the issue wasn't covered under warranty. Because of the increasing blowback, Tesla changed course and issued extended warranties for the older MCU unit but refused to issue a recall. US safety regulators believe it should.

The Associated Press reports the National Highway Traffic Safety Administration informed Tesla earlier this week it has determined those touchscreens are defective and pose numerous safety risks; the backup cameras can go dark and the defrosters could malfunction are just two examples. Even Autopilot can be affected by screen failures resulting in a loss of audible safety alerts. Therefore, a recall of around 159,000 vehicles potentially equipped with these defective touchscreens must happen.

The NHTSA began investigating the matter last June and upgraded the matter to an engineering analysis in November. The technical investigation revealed problems and determined the screens will fail in five to six years. "The lack of a functioning windshield defogging and defrosting system may decrease the driver's visibility in inclement weather, increasing the risk of a crash," the letter said.

Furthermore, the NHTSA discovered over 12,000 customer complaints and other related reports related to the screens - from data submitted by Tesla. Equally important is that the safety agency determined Tesla's attempts to fix the problem numerous times with over-the-air updates were insufficient. The agency's letter also stated that if the automaker decides against a recall, it must explain why.

The pressure can potentially heat up for Tesla since the agency has the power to schedule public meetings on the issue and, if necessary, even turn to the Justice Department to pursue legal action. Tesla has not commented on the matter but this is something it cannot ignore.