the yellow check engine sign came on today while i was on the freeway....i took it immediately to the dealer...he said that the fuel mixture sensor was "out of specs" and that it needed to be fixed....he told me to bring the car in on monday...i asked him if its ok to drive the car with the check engine sign on...he said its perfectly alright in this instance because the computer on the car will adjust for the sensor problem...i don't know if he's right or not...the car is not in limp mode or anthing...i have a trip this weekend but i don't know if i should take the clk or my other car...please advise...is it ok to drive or is the dealer wrong....thanks in advance

The computer can "adjust" the fuel mixture aprox 30% either direction(rich or lean) from mean value, after that much correction in either direction the check engine lamp comes on. That means the computer can NO longer correct the fuel mixture. Running a engine at the "lean" stop isn't good at highway speed. If they had time to check the car why didn't they install the sensor? Around town should be OK but a TRIP could cause problems.

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i have no idea why they didn't change the sensor...the service guy just said that they didn't have time and that i would have to bring it back in on monday...whats funny is that i took the car out to buy something today and the light was still on...but about twenty minutes into the drive...it suddenly turned off and has not turned on since...please advise...