I own a c240 2001 and recently it just has been turning off in the middle of the street while in traffic or stopped at a red light. I changed all the filters and put in fuel injection , nothing seems to work. It had "Check Coolant Level " on for sometime, but the coolant level is fine. Also we took it to AUTOZONE and the machine pulled up 2 problems, PO 175 (O2 sensor) and PO 335 (crank sensor), what are these and what do they mean. Mercedes is going to charge me and arm and a leg to diagnos it let along the labor to fix it and parts. So, I was hoping that someone would know what these PO's mean and help me out!!! thanks!!

Desperate~

Well, a defective crank sensor could cause such a problem. It signals the ignition the position of the crankshaft so it knows when to fire. No signal -> no spark. At least that's on a older Bosch CIS ignition, but I guess that function is still the same on your car. Regards, Bruno

Yep. Sounds like you need one of these.
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1FU1CD1PL1N70O0JVD&year=2001&make=MB&model=C-240-001&category=F&part=Reference+Sensor
Cranksensor.
I would leave the O2 sensor for now.

__________________
2007 C 230 Sport.

I agree with BRUNO, a crank position sensor is a good place to start. It isn't very hard to install (kinda a pain on some cars though, forgot how it is on a c240). You can also take it to a reputable independent shop for them to fix. That should cost less. What part of the country do you live in?