I've seen various models with blue-shifted LED headlights. Most notably, Toyota and Tesla. I have a photo on my phone somewhere.

Has anyone else seen such a phenomenon? I assume it's the same phosphor detachment from high ambient heat suffered by some earlier LED streetlights?

I have seen the same thing. Usually I don't see the purplish-tint associated with partial phosphor detatchment, and usually I don't see the ~monochromatic blue associated with complete phosphor detachment. I always assumed it was just different color headlights that you could get (10,000K blue for example). But of course I could be wrong.

On the rare occasions that I do see purple, that can be at least partially explained by the availability of 12,000K headlights, which are purple-ish in color. Or it could of course be partial phosphor detachment.

Never heard of phosphor detachment in headlights, but I am sure it is possible. I guess the color could be either from that or from the driver's color preference. Can't really know which one without closer physical inspection though (or using a spectrometer maybe).

Very interesting, I haven't seen that here, and I do pay attention to cars. I presume the Toyotas and Teslas in the USA are locally made, but I've got no idea about the lights...

I am trying to find the crystal-clear photo I took of a ~2020 Model 3 with this phenomenon. I was standing next to him at a light and managed to capture both the good and bad headlight side by side. While he was driving (one lane road, two or so cars ahead), you could see the bluish-purple UV-colored cast on the surrounding roadways and tree trunks. Unfortunately, my phone is not "tagging" these photos on the map (particular location), and nor are they showing up in my gallery's "Enhanced AI Search". I also do not remember the approximate time of year I took them... all I know is "2025, particular roadway that I take every Tues and Thurs evening to piano." 

Reason why I made this thread was because I noticed a similar, albeit less severe case of this on a 2023 Toyota Corolla yesterday. Driver's side was normal, while passenger's side was blue-shifted.

Very interesting, if you can find that picture, I'd love to see it.

Fact is, the automotive headlights are driving the LEDs way harder than it is common with general lighting. Paertially because auto headlights needprecise beam control which needs high intensity packaged to a small area, partly because car headlights use to be designed by far shorter lifetime than general lighting, because simply the cars do not run that many hours over their runtime. Normal passenger car lifetime of 300000km/200000mi means about 5k hours running, headlights are on for barely 1/3 of that, so lifetime of 2k hours means the headlight will last the whole car life, which means less than 1/10 of typical lifetime requirement vs general lighting. And the headlights are really engineered to last just that, to get the required performance at the lowest cost possible, so some degradation effects may already show up, mainly when they do not constitute headlight failure.

And the hard drive may mean different degradation effects than usual for general lighting become dominant. And then there is many years of off state parking time, when the humidity may corrode things without being drawn out by the heat of normal operation.

@Medved -- Good to know! Seems logical that they are engineered to last no longer than the lifetime of the car. I simply find it bizarre that OEMs are sourcing lower-quality assemblies which fail in these bizarre ways... on newer vehicles nonetheless. I think that Corolla I mentioned is still under warranty, so I assume it would be replaced if brought to a Toyota dealer... I find it interesting that it's also an anomalous process, and only few cars are actually plagued with the issue, and not even both lights... this variation and seeming "randomness" is what I find most intriguing. So bizarre to me that they do not fail in pairs as one would expect.

The problem with the "engineering on the edge" is, there is practically no room for any design error, no room for any effect that has been incorrectly neglected. And it is by far not only about normal phzsical or chemical effects, but also about what the real manufacturing is doing on the production floor vs what was assumed during the design.

Why that the LEDs inside automotive headlights would be driven harder than in general lighting? They should be driven the same.

@Medved — True, I just find it odd that they do not fail in batches / pairs of two, and instead one suffers early failure due to poor factory floor quality control? Seems to be the only explanation... probably made overseas in very high volume, and not every unit is perfect...