Last month, we reported on a Tesla Model S catching on fire during a test drive event in France. All 3 occupants, a couple that was test driving the car and a Tesla employee, were able to exit in time thanks to the vehicle sending out an alert warning them of a problem.

At the time, it wasn’t clear what was the problem in question, but Tesla quickly launched an investigation and now they think they found the issue.

According to witnesses, the Model S melted down and was completely destroyed within 5 minutes, which could have complicated the 3-week long investigation. Nonetheless, the automaker seems to have found the issue.

Tesla says that the Model S used for the test drive, a 2016 Model S 90D, had “bolted electrical connection” that were manually tightened by a human instead of by robots. The company points to one of those “bolted electrical connections” as being “improperly tightened” which caused the fire.

Charles Delaville, Tesla’s communication manager in France, told Fox News:

“Usually, these electrical connections are installed by a robot, but for this car this connection was installed manually. There has never been a similar incident in another one of our cars,”

Indeed, that’s what is interesting about this incident. While Tesla vehicles have gone up in flames before (though no more than its gas-powered counterparts), it was almost always after some severe accident with the exception of a Model S fire while charging in Norway.

We are talking about accidents like the one Tesla described after introducing an underbody shield to protect the battery pack:

“The vehicle impacted a roundabout at 110 mph, shearing off 15 feet of concrete curbwall and tearing off the left front wheel, then smashing through an eight foot tall buttressed concrete wall on the other side of the road and tearing off the right front wheel, before crashing into a tree. The driver stepped out and walked away with no permanent injuries and a fire, again limited to the front section of the vehicle, started several minutes later.”

There’s no word on why the Model S in question had bolted electrical connections manually tightened by a human instead of by robots. We asked Tesla for more details on the investigation and we will update if we find out anything interesting.

FTC: We use income earning auto affiliate links. More.

Subscribe to Electrek on YouTube for exclusive videos and subscribe to the podcast.