Crossposting from the C32 forum:

I finally tired of the mis-matched colors of my HID headlights. I assumed one had been replaced by the previous owner and the colors were different due to different ages, or possibly different color temperatures. I just installed two new 35W, 4300K xenon bulbs and the colors are still different!

What can cause such a thing? A bad ballast? Both lights fire instantly with no flicker, and I have no malfunctions present in the DIC. One light looks normal and the other has a pink/purple cast to it (both with the original bulbs and with the brand-new bulbs).

Thanx for any advice; I'm stumped!

You should post a picture as a reference ....

I can prolly do that; gotta wait till it gets darker...

If one ballast is having trouble keeping the power to the bulbs at the correct level constantly, then the output will be different. One may be more blue because the ballast is still in the "warm up" stage of igniting the bulbs, and can't establish the "cruising altitude" (if that makes sense) voltage/amperage/etc. Old ballasts are prone to this, along with cheap ballasts. You may even see the arc "dance" and the light beam might have the slightest flicker. (Not on-off flicker, but it slightly dims, or the beam moves about.)

If your ballasts have never been replaced, 9 years seems like a good run. Time to swap them out. If they're aftermarket ones that aren't the best quality, a year or two seems to be a fair life-span.

Are the lights OEM? Are you using quality bulbs? if no to either that explains it

I just noticed one side is a different color than the other one. Let me know what it was.

I have the same problem. One year old 55W 6000K DDM Tuning HID's.

My left headlight gradually over time has changed to almost a yellowish-greenish white while the right headlight is still the bluish white like what a 6000K HID is supposed to look like.

Any idea if its the bulb or the ballast thats causing this?