Have Mercedes Questions? Ask a Mechanic for Answers ASAP
Hi, my name is***** usual problem on the S420 is a faulty front seat belt buckle. You will need to get the car connected to a Mercedes tester that can read out the fault codes in the seat belt system. The fault codes will tell you which part is bad. If you are unable to do that you can try swapping out the front seat belt buckles and see if the light turns off.
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