2000 328i Sensors

[Brendan52]

The sensor(light) for the airbag is on. My mechanic says the bag will not work if light is on. Is this true?? Also, the light for check engine is on and at various times other lights come on. The cars runs fine, do I need to address the warning lights?

[Mach 5]

Yes, you need to address the lights, your mechanic is correct in that if the light is on then the airbag MAY not go off in the event of a collision. (It could be something as simple as a faulty switch at the seatbelt.
An intermittant CEL is usually an indication of a faulty O2 sensor. But could indicate a more severe problem (possible cam sensor gone bad, etc.) Autozone is reading codes for free these days so drive down if you have one near and find out what is wrong.
Ben

[PMB]

I don't know about the engine and other lights but my airbag light came on a while ago. I took it to my dealer who evaluated it into being a faulty sensor. I took it in for the new sensor to be fitted and no sensor was fitted, rather they changed the wiring where the seatbelt buckle clips in to bypass (basically) the switch. This is a well known fault on the E46, especially early ones. This specific problem does not prevent your airbag from deploying. A faulty sensor does though.

Best of luck with it.