As Xenon HID ballast / bulbs degrade over time and use, their performance will change. It is important that ballasts and bulbs stay balanced to work well together. Older parts are likely to cause newer parts to fail prematurely. For this reason, ballasts, bulbs, and igniters are not warrantied when purchased individually.
If your Xenon HID kit / parts are 3 years or older, we suggest that you replace bulbs, ballasts, and igniters (if not built into the bulb or ballast) at the same time for optimal performance and longevity.