One problem related to crankcase (pcv) has been reported for the 2002 Mercedes Benz C230. The most recently reported issues are listed below.
Check engine light illuminated after 1,000 miles after I bought the car used. The car had 47,000 miles. The engine was not performing as well as it had been. The dealer ran a diagnostic which revealed six sensors had failed and needed replacing. Upon subsequent investigation the dealer found that oil had leaked into the sensors wiring harness and contaminated the sensors.