I had my car for two years ML 320-2001. I just took it to the 60.000 service. I did not go to the dealer; I have someone who is good with European cars.

He told me to go to the dealer because every time I turn the car on I have a yellow light that say" low range" it has something to do with the 4 wheeler.
Can some one tell me what’s wrong with the car and how much something like that can cost? the light is off after a few sec. My mechanic told me he can't repair it. Thanks.