scottonfire

So the Check Engine light goes off today. Even though there's nothing that feels wrong with the car, I take it in to Pep Boys. Dude says the something or other, but essentially he can't pull any codes from the OBDII reader.

History- last thing I did was put chevron w/ techron fuel cleaner in a 12 gallon tank, drove till E, did one more round of chevron w/ techron fuel cleaner- but that was like 10 days ago. Before that I replaced the transmission mount and a month ago I fixed a vacuum oil leak and camshaft solenoid leak.

Mechanic thinks it's electric issue- possibly one for not being able to pull the codes- only thing I did electric was intall aux. input (OEM mercedes plug) to play music for my phone- but this was like 2 months ago and it's been working fine.

mercedes4ever

Get a Star reading.

RWDlifer

W203s are picky when it comes to what scanner will work pulling codes. I went through several..heck, I have one that works on the 3 series but won't pull codes from the 203.
As far as your check engine light, it's worth noting that it's cause is emissions; either a sensor, leak or adaptation. All CELs are in one way or another tied to emissions.
+1 on the star reading...

Khan28

Perhaps their particular scanner isn't able to communicate with the car's computer. You can try buying one or taking it to a MB specialist and have them do the reading for you. I have a cheap Innova scanner I bought for $39 on sale and it works great, it probably paid for itself 10 times over because of the potential repairs it saved me. It worked in my Dad's old GM, his Acura TL, my Mom's Nissan Sentra, my old Nissan Maxima and worked the one time my CEL came on in the Benz.