Thanx Steve for the fast respons..No The "vericode" doest give you actual values...i think thats what mercedes was refering when they said that they measasuer actuall components of gasses...on the other hand..just after i posted the topic , i had to dive somewhere and when i turned on the engine the "check engine" light didnt come on again... so right now im set..(the car was parked for about an hour inbetween)...i had similar problams with my 88 300E as soon as the warm weather hit the Engine light came on and the car was stalling...couldnr figure out for about 3 years whats wrong at that time i took the car to mercedes spet a fortune with no result..(thats why im hesitant to take it there ) after a lot of reading and eleminations,testing(all on my own) i reheated ALL the contacts on the computer and that was the problam ..(damn i was happy and proud..lol) do you think that i might have something like this again??...or should i spend the money and have atleast the exhaust gas tested for values? Thanx