I have a 2007 IS250 AWD. I have stock headlights which I assume are halogens. The left light comes on whenever it is turned on manually or by the light sensor. Soon after it will go out while the right light stays on. If I turn the headlights off and back on it will come back on. Eventually it will go out again, and I can repeat over and over.

What I don't know because I don't know enough about halogen bulbs is, is this a sign of a bad bulb or bad wiring? It's been happening for a year. If the bulb was bad wouldn't it just go out and never come on again? Doesn't it have to be wiring if you can turn them off and back on and the light comes on? And if it is wiring how could it work when first turned on but then fail and then work again if flicked off and on?

I'm worried I'll pay for a new lamp and the same problem will occur.