The O2 sensor part number is 006-542-96-17 & list is $162(check partsshop!!).
Takes about 15-30 minutes to replace, depending on rust!!
There are GENERIC O2 sensors that will work, this car uses a 3 wire sensor!
Diagnostic times vary due to many different items.
MOST cold running problems aren't related to the O2 sensor but to the coolant temperature sensor.
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)