The federal government wants to know more about Tesla’s batteries, its charging, its software upgrades, and incidents relating to reported fires—among many other details concerning the majority of Tesla Model S fastbacks and Model X SUVs ever built.

In a letter, dated October 24, the National Highway Traffic Safety Administration notes that it has opened a Defect Petition to evaluate a petition filed September 17, asking it “to initiate a Defect Investigation into the recent set of software updates, including software updates 2019.16.1 and 2019.16.2 and all subsequent updates issued by Tesla, Inc. to its Model S and Model X vehicles, which have been alleged to be issued by Tesla in response to the alarming number of car fires that have occurred worldwide.”

2018 Tesla Model X

2018 Tesla Model X

The terminology is important to distinguish. NHTSA has not yet opened a formal Defect Investigation on the matter, but the information request would normally be a next step toward doing that. A Defect Investigation could result in a recall or prescribed fix for the issue.

The original letter requesting the investigation was filed by Edward C. Chen, an Irvine, California attorney, seeking to represent a group of owners. 

The NHTSA letter to Tesla notes that the request covers Tesla Model S and Model X vehicles from model year 2012 through 2019 that were manufactured for sale or lease in the U.S. It doesn’t pertain to the Model 3, which uses a completely different cell. 

2019 Tesla Model S

2019 Tesla Model S

The letter isn’t unusual in that it asks Tesla to report the number of claims and reports the company might have collected on its own. What’s unusual about the letter is the depth and breadth of the information request, and how technical it is. Regarding the software updates, Tesla is requested to provide deep descriptions of the updates, why vehicles chosen received them, what owners were told, their effect on driving range, and their potential effect on battery-fire risk. It also asks Tesla for what it knows regarding the incidents in the related defect petition, in terms of the state of charge, mileage, and recent type of charging. 

Tesla is also asked to describe “cell shorting failure mechanisms,” the way in which its systems detect the shorts, and how the system manages detected ones.

Another unusual request from the federal agency—and an indication that this request is in uncharted territory, in how it relates to over-the-air updates—is that it asks for planned updates to be deployed in the next 120 days. 

Green Car Reports has reached out to Tesla for an official statement, as well as verification on an earlier figure that the company put out: that the likelihood of a gasoline-vehicle fire is about 11 times greater than for a Tesla. 

The NHTSA letter requires a response from Tesla by November 28. Failure to respond could result in civil penalties, but it also gives Tesla the opportunity to separate “business confidential information.”