I have a light on the dash and unsure what it means. The car is a 1998 e200. The light is on the left hand side under bas/asr light. Looks like a steering wheel with a wavy line underneath. Also low coolant light is on but coolant full. Is the sensor the llittle tube at top of radiator bottle? And finally what wheels have brake sensors on please? Wear sensor keeps flickering even though brakes are fine,no squeaking or grinding and pads look ok. Thanks.