Getting Bulb Failure Low Beam, tested ballast, new bulb
 

Good morning,

My wife drives a 2007 XC90 with factory HID headlights. One day the driver's side light started flickering intermittently and the car gave an error message: "bulb failure - low beam" so I started doing some research. I found several forums that suggested that the ballast could be the issue, so I switched the ballasts from left to right to see if the problem would travel to the passenger side. It did not, so I ruled out the ballast and ordered a new bulb. I installed the new bulb over the weekend, it lit right up, so I figured I was good to go. Turns out I was wrong: after about 30 seconds, the new bulb goes out completely and I see the error message again.

I thought I noticed a loud humming sound after installing the new bulb (it was a Philips DS1, by the way) but I wasn't sure if it was coming from the headlight or somewhere else in the engine compartment because I had the key on but the engine off (you know, sometimes electrical components hum under those circumstances).

Anyway, any help would be greatly appreciated. Thanks!