preyx

While driving home from my friend's house last Thursday, the "Check Engine" light lit up. I scheduled an appointment for Tuesday afternoon, so I don't know what the problem is yet. The car seems to be driving normally, and I'm about 900 miles from a Service A (with my odometer at around 33100 mi). The only guess that I have is that the coolant may be low, since the temp fluctuates within a +- 4C range, nothing critical, but still noteworthy. Anyways, if anybody is familiar with the warning light, and could venture a few guesses to the problem, I'd appreciate it. I'll report back when I hear what the dealer found.

Harris

Guess 1: didnt turn the fuel cap properly
Guess 2: air pump
Guess 3: mass air flow sensor

Should be one of the three above!

rrf

Coolant problems would normally be reflected in coolant level and that is a separate error.

Maybe add O2 sensor problem to the list above. My guess is #2 though.

FIXEDupW209

9 out of 10 times its the fuel cap....mercedes warns that if its not properfaly tightened the light will come on and the car will need to be brought in to turn it off...my guess its that and guaranteed thats the first thing they are gonna ask you and check.

viper

The coolant temperature sensor is a known problem. This will turn on your check engine light if it is faulty. You also mention a temperature fluctuation so it points in this direction.