[PLP]

It is not easy to track if your experience is limited.
Do not take it offensively, it is the sad truth about High Intensity Discharge (HID) systems.
First make sure you actually have working headlight switch, or verify you get power coming to the assemblies.
It is unlikely that both of them are dead. Xenon gas lamps do not die so often. It takes a while.

There are 3 parts of it.
Ballast, igniter, and the lamp (it is technically a lamp, not a light bulb… as the light bulb needs to have a filament. HID does not, because the hot gas glows. Like neon signs).

So, any of the 3 components may be dead or have a faulty connection.

First I would, after verifying power coming it, check all the connection inside the assembly. Also, is the ballast actually attached to the headlight? It is possible you got a set WITHOUT the ballast.
Happened before…
If everything is in place, continue.

The best approach for your is you is to swap the lamps (bulbs) left with right.
If that does not help – well, get a new one. Buy a pair of D2S, 4300 K. Do not go above 5000 K. No, you do not get more light. It is the opposite – 4300 K provides the most intensity and it keeps dropping the higher you go.

If that still does not work – next step is to investigate the ballasts. Those might be more expensive to get. I have never had Boxster’s OEM HID assembly in my hands, so I cannot advise if you could use some aftermarket replacement.

Or, before you get there – get a cheap ballast from eBay that works with D2S and check your OEM lamps (bulbs).


A note on HID systems.

They are powered by 12 V DC (Direct Current) from the car.
The ballast converts DC into AC (Alternative Current) and bumps the voltage to about 85 V. This voltage is needed to keep the gas lit.
However, to light it up, you need a much higher voltage. Hence the igniter comes in and bumps the potential to 20’000 V (or so – depends on setup). This spark flies through the lamp and gets the initial flicker. Once it is lit and the current flow is established, the 85 V kicks in and maintains the light.

Why AC? If you look closely into the HID lamp, you will see two electrodes on the ends of the tiny bulb inside the long glass barrel. If you were to use DC, one of the electrodes would accumulate deposits while the other one would start degrading. In the end, in a very short time, the light would start shifting towards one of the ends resulting in, initially, poor light distribution (like improperly inserted light bulb in halogen) and then lower light output.
With AC this process keeps going back and forth and maintains performance.