1 headlight works on low beam. All 4 work on high beam....

[papanoel]

So one headlight works on low beam but if I put the high beams on all 4 work.
Do low beam lights have 2 filaments?

[Chris 16409]

The low beam lights have a low beam filament and a high beam filament. So one of your low beam filaments is burnt out. This happened on my car. You might as well replace both bulbs. You don't know when the other bulb will go bad.

[papanoel]

Thanks. I replaced one side 3 months ago.