There is a lambda tester that is available from Baum tools for the testing of the O2 sensor and the fuel system's adjustment in general...I believe it costs about 300.00 US dollars.

------------------
Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM