U.S. Regulators Expand Safety Probe to 159,000 Tesla Vehicles Over Touchscreen Display Failures

resource from: Reuters   

Memory wear out can cause Tesla's center-mounted touchscreen to fail on the Model S and X built through early 2018.

The U.S. National Highway Traffic Safety Administration (NHTSA) said on Monday it was expanding its probe into nearly 159,000 Tesla Model S and Model X vehicles over reports of the center touchscreen display failures, Reuters reports. 

The expanding investigation is being upgraded to an "engineering analysis" the administration said, which is required before the NHTSA can make steps to formally recall a vehicle.

The part in question is the memory control unit (MCU)  supporting Tesla's center-mounted touchscreen display, which gives a driver access to most of the vehicle's controls. It is used for entertainment, maps, navigation, and heating and air conditioning controls. The NHTSA opened a preliminary evaluation in June after Tesla owners reported a high number of touchscreen failures.

The NHTSA said it has reviewed 12,523 claims and complaints about the issue, which would impact around 8% of the vehicles under investigation.

Since the dashboard mounted display is the only way to access most vehicle features and subsystem control menus, the loss of the touchscreen results in the loss of the rear view camera feed when putting the vehicle in reverse. 

Other systems that are not accessible without using the touchscreen are the vehicle's rear window defogger, as well as the audible chimes for the turn signals and those that confirm the activation of Tesla's Autopilot automated driving feature.

Some Tesla owners however complained that the failures could result in loss of charging ability and that other safety alerts could be impacted. One driver said he could not clear fogged windows because he could not change climate controls, according to Reuters.

NHTSA said however the failure does not affect vehicle-control systems.

The initial probe launched in June was for roughly 63,000 Model S sedans built between 2012 and 2018, but now its investigation has been expanded to include the 2016-2018 Model X vehicles. 

A Closer Look at the Problem

The media control unit (MCU) for the touchscreen display in the Tesla Model S and X vehicles built until early 2018 used a Linux-based open source operating system running on a NVIDIA Tegra 3 SoC which was introduced back in 2011. 

The Linux OS is stored on an 8GB embedded Multimedia Controller (eMMC) flash memory device instead of using a removable flash storage device. Although flash memory is widely used and is considered highly reliable for millions of electronic devices, one drawback for its use in the auto industry is that it has a finite number of rear/write cycles, the NHTSA said.

In early Tesla vehicles, the log files generated by the Linux operating system were being written to a non-replaceable storage device that was soldered onto the motherboard. In addition, Tesla's graphical interface generated its own set of internal log messages, even though its unlikely that anyone would ever need to access them in the future. 

During normal vehicle operation, the size of these log files continued to grow. But the nearly continuous writing of data to the eMMC chips on the older Nvidia Tegra 3 MCUs led to their degradation over time. The process is known as "memory wear out " where the eMMC can no longer reliably store data.

If this happens, Tesla owners might experience erratic operation of the display, very slow response times, map rendering issues when using navigation, random reboots or complete a completely black screen. 

NHTSA said the data showed "failure rates over 30% in certain build months and accelerating failure trends after 3 to 4 years-in-service."

The NHTSA added that flash memory failures resulting from memory wear-out "are likely to occur after periods of progressively degraded performance symptoms, including longer power-up times, more frequent touch screen resets, intermittent loss of cellular connectivity or disruptions in the vehicle's navigation system."

Tesla eventually solved the problem for vehicles built after 2018. These models use an Intel Atom microprocessor for the MCU. The Intel Atom uses error-correcting code (ECC) memory that offers memory failure protection. This type of computer memory can detect and correct data corruption. ECC memory is typically used in critical applications where data corruption cannot be tolerated.

Tesla said it has received 2,399 complaints and field reports, 7,777 warranty claims, and 4,746 non-warranty claims related to MCU replacements.

Many complaints said Tesla requires owners to pay to replace the expensive unit once warranties expire. Replacing the touchscreen cost owners on average $1,300. In July, Tesla extended the warranty period on the display to 8 years or 100,000 miles. 

On Nov 9, Tesla updated its Warranty Adjustment Program in order to reimburse owners who already had to pay for the repair.

Tesla used the same display screen in 159,000 2012-2018 Model S and 2016-2018 Model X SUVs vehicles produced by Tesla until early 2018.

To help prevent the problem for the thousands of vehicles with the older eMMC, Tesla pushed a number of over-the-air updates to its vehicles in order to help "to mitigate the effects of MCU failure," the NHTSA said. 

Among the new updates are changes to reduce memory usage of the embedded multimedia flash memory card, improving storage management strategies, and changing the control logic for turn signal activation.

resource from: Reuters

Eric Walz

Originally hailing from New Jersey, Eric is a automotive & technology reporter covering the high-tech industry here in Silicon Valley. He has over 15 years of automotive experience and a bachelors degree in computer science. These skills, combined with technical writing and news reporting, allows him to fully understand and identify new and innovative technologies in the auto industry and beyond. He has worked at Uber on self-driving cars and as a technical writer, helping people to understand and work with technology.