HID bulb or ballast issue?

manysaver

So I have HID bulbs D4S in my car and I've worked out that the nearside bulb may sometimes dim and then go out.

Apparently this could be the ballast or it could be the bulb. Any ideas ?

unforeseen

You seemed to have covered all the bases.

JustAnotherSaver

The bulbs are fairly cheap themselves to change so i’d probably start there. HIDS4U would be one website. I’ve used another but the name escapes me at the moment (no, it wasn’t eBay).

alan_d

Swap the bulbs from one side to the other and see if the fault moves with it. This will prove if the bulb or the ballast is at fault.
It's most likely to be the bulb however - and also likely that the other one will fail soon, so suggest buying a pair.

manysaver

The problem is it's not very easy to change the bulbs apparently 1.5 hours labour....

born_again

Factory fit or after market?

If factory than what about warranty?

twhitehousescat

"bulbs" are not a warranty item