A good old fashioned failure. Happened in my 2008 C300 4MATIC in 2016. Dealer claimed "age". Can't be repaired using old parts and you will sign a lot of paperwork as it is considered a "TRP" Theft Relevant Part". Expect a near $1000 repair bill.
Search Mercedes-Benz C-Class Questions
Mercedes-Benz C-Class Experts
Related Models For Sale
Used Cars For Sale