Low Beam Failure
 

I have a 2011 S60 T6. What would cause a low beam failure? I changed the bulb today and that had no effect.

Do you have Halogen or HID bulbs? (both were offered)

HID. I bought a D3S bulb.

Try the new bulb in the other side. HID bulbs have ballasts. A ballast is a transformer that steps up the voltage to excite the gas inside the bulb and make them glow. The same way a fluorescent tube or a neon sign works. You might be able to swap ballasts from left to right to test them. They are mounted on or in the headlamp assembly.

Thanks. I'm dumb. I didn't even think about trying it in the driver's side. At least the headlights are easy to get out.

It is very nice that they updated the Headlights in P3 so you don't have to take the bumpers off anymore.

I have the same vehicle with xenon HID's and I actually had two problems. One, the ballast on one side did fail. During the same time I replaced it I put new bulbs in. Neither bulb would light. I then exchanged the bulbs for another brand and they work fine. Go figure.