The National Highway Traffic Safety Administration is investigating nearly 2.6 million Tesla vehicles over reports that multiple crashes were caused by a feature that allows users to control their cars remotely.

The NHTSA opened the probe on Monday after receiving four reports of crashes caused by either Tesla's Smart Summon or Actually Smart Summon features. According to the NHTSA, both features "allow a user to remotely move the vehicle to the user or to another designated location, through (the) use of a phone app."

All four incidents received and reviewed by the Office of Defects Investigation (ODI) involved the Tesla vehicles operating in Actually Smart Summon and failing to "detect posts or parked vehicles, resulting in a crash," the NHTSA said.

In October, the NHTSA opened an investigation into 2.4 million Tesla vehicles equipped with Full Self-Driving (FSD) software after four collisions were reported, including a fatal 2023 crash.

Here is what to know about the ongoing probe, including what Tesla models are affected.

What is Actually Smart Summon?

Actually Smart Summon, which replaced the EV-maker's original Smart Summon feature, allows users to "summon" their vehicle by using an app on their cell phone, Tesla demonstrated in a tutorial video posted in October.

According to the NHTSA, ODI had received 12 Smart Summon-related complaints alleging crash typology similar to the crashes experienced by users of Actually Smart Summon during sessions that offered little time for them to react.

"ODI is aware of multiple crash allegations, involving both Smart Summon and Actually Smart Summon, where the user had too little reaction time to avoid a crash, either with the available line of sight or releasing the phone app button, which stops the vehicle’s movement," the agency said.

What is the NHTSA investigating?

In addition to investigating Actually Smart Summon's capabilities concerning crashes, NHTSA's ODI will look into the feature's operation and field performance in FSD-equipped vehicles and vehicles included in free trial offers.

The NHTSA will also evaluate the top speed that a vehicle can reach while Actually Smart Summon is engaged, especially on public roads. The agency's preliminary evaluation of the feature will be reviewing the remote control through the phone app, and how it impacts connectivity delays and the system's performance in unforeseen conditions.

After the NHTSA's preliminary evaluation of the feature, the agency must determine whether or not to update the probe to an engineering analysis before seeking a recall, Reuters reported.

What Tesla models are a part of the probe?

The investigation includes the following Tesla vehicles equipped with full self-driving features in various model years:

• Model S 2016-2025
• Model X 2016-2025
• Model 3 2017-2025
• Model Y 2020-2025