How do I reset or service coolant light?

If the level is good (i.e. topped off when the engine is cold) and the light remains on you may have a defective coolant level sensor. Some E46's have the coolant level sensor built into the coolant reservoir and some are at the bottom or side of the reservoir and can be replaced separately. Check it by unplugging the sensor wire from your reservoir and connect it to that of an empty known working one and flip it upside down. If the light goes out there's your answer. I hope this helps, Kind regards, Stephane Grabina BMW Excluservice Rockville, MD 20852 www.bmwexcluservice.com