2019.12.1 my tesla breaks for neither man nor car

I've been fairly quiet about the interesting behaviour of my Model X, Pensive, as I've been waiting for a response from Tesla regarding the on-going issues in my car. Since I currently don't have another option, it continues to be my daily drive, and it updated to 2019.12.1 on April 29th followed by a point release on May 3rd to 2019.12.2. I wrote about some of the initial observations , and was excited that the Web browser was finally once again usable (it'd been broken in one way or another since upgrading to v9).

Quirks and Annoyances

Over the last few months, a few quirks have manifested themselves in sometimes interesting ways.

Finicky AutoPilot, refusing to continue. AutoSteer will routinely be doing fine, following with traffic along the road, and slow to a stop (e.g. at a traffic light). However, when traffic begins to move again, or you release the brake hold if it was applied, AutoPilot warns about disengaging and hands control back to the driver. There are a lot of reasons why AutoPilot might do this, so in itself it:s not unexpected, but I've never seen it happen as often and seemingly whimsically as it is doing it under 2019.12.1. My current assumption at a traffic light or slow stop-and-go traffic is that I'll need to resume control of the car to get going again—considering that stop-and-go traffic is one of the most beneficial times to use AutoSteer, this is rather annoying.

Illegible text. I do not recall having come across this behaviour before, but getting into my car the text in much (but not all) of the UI was illegible. Soft-rebooting didn't solve this, but a full poweroff appears to have worked.

Remote environmental controls are not working. Since around the upgrade to 2019.8.5, the phone application has been unable to toggle the environmental controls on the vehicle, even though everything else appears to continue to work1. I do not know exactly when this started, so it is unclear to me if this is an issue with the software on the vehicle or an issue with Tesla's cloud system. I've tried it several times, over multiple days, so even if it's on the cloud's side, it appears to be long-lived.

Regressions and Continuing Issues

Charge port door is non-responsive. When I first received my Model X, Pensive,, the chargeport door physically was catching, preventing it from closing on its own, and this was fixed at the first service appointment. Subsequent issues have all been somewhere in the software or electronics. Previously, the vehicle had intermittently failed to open the charging port from the button on the Tesla charger, but with 2019.12.1 it is consistently not opening through any remote means. In order to open the port, I need to use the center screen.

Automatically triggering garage doors doesn't work. Triggering the garage door not working was a previous issue, as well. It seemed to get better for a while, but is once again needing to be manually triggered.

Unexplainable Breaking

The most annoying issue, however, is that the car seems to fairly frequently simply slow-down or apply the breaks. This has happened regardless of road, lighting, and time of day. The most unexplainable was at night on the Interstate when, without traffic, the car slowed to 35mph before slowly resuming its original speed of 55mph. Other times, it's done this with moderate traffic on the Interstate necessitating quick overrides via the accelerator pedal to avoid instigating a potential rear-ending.

The behaviour here is different from the phantom cars I talked about last year; back then, the car was seeing cars on the road, presumably through misinterpreting shadows and contrast changes in usually harsh lighting, and I hypothesised that lead to some otherwise unexplained applications of emergency breaking. The current behaviour could very well be related, but is much more gradual (and doesn't result in any alerts), slowing the vehicle as if in traffic rather than an unexpected hard-breaking event. It does behave similarly to behaviour seen under 2019.8 when we drove to New York, but under 2019.12 it is happening with much greater frequency.


  1. Unlike under 2018.20 when there were more general connectivity issues