Hello Mercedes People,
I have a 2012 C250 that generates heavy gasoline fumes if I travel on the freeway for an extended time (30 minutes or more}. I recently had my air bags replaced because of the recall at Mercedes in Walnut Creek, and asked them to diagnose what is causing the gas fumes. They did diagnostics tests including compression, but could not find any explanation for the gas fumes. They did say that the oil smelled like gasoline, but had no solution for the problem. The car has does have 120000 but, other than this brutal gas smell, runs great and is well maintained including frequent oil changes. I had received a CEL that indicated my thermostat needed to be replaced, but if I cleared the code, the CEL would go away. I have researched this problem extensively, and I did find some information about when a thermostat goes out and remains open, it can cause the car to run rich. Apparently the CPU will send additional gas because the (cold engine) open thermostat makes the engine warm up too slow. I replaced the thermostat and prayed it would fix the gas fumes, I am so bummed it did not. That procedure has caused another problem. Where the turbo connects to the air intake pipe, is a very difficult place to reach and/or get any leverage. The plastic intake pipe has a lip that is super tight and will not allow the connection to seat all the way secure to the collar at the turbo. Any suggestion that can get that seated fully?
Does anyone know what might be causing gas in my oil. I had also read posts saying it could be caused by the PCV valve or the crankcase vent valve? I cannot find a PCV valve replacement part (most parts stores say it is discontinued) for this car, which I believe is the plastic cover backside engine near the firewall on the passenger side?. I am also confused about where the crankcase vent valve and hose are located? There must be someone else who has had these same symptoms and could help me finally solve this issue? Please HELP?
Thank you sincerely.....Knightstale04

 

Hey what up man, I also have the same issue. Gas in my oil/fumes in cabin. I've been told by some people in a Benz group on FB, (I recommend you join it), that it is indeed the PCV/Crankcase breather valve that may be causing this issue. I called my dealership today to get the part from them, which they have, but want 77 bucks for the part. I've been able to find parts on PartsGeek.com and am planning on doing it. I have been told that once you replace it though you need to do an oil change right after. I hope this helps and LMK if you want to join lol

 

I have the same issue. Was wondering if changing your sensor worked. Please advise!
Blessings!

 

Knightstale04 I have the exact same thing on my c200 it’s 2012 1.8 turbo m271 Evo engine it’s the exact same motor , do you find something? I don’t find anything about PCV valve/ crankcase purge system, and when put the foot down to the throttle spits oil from the dipstick , the car don’t show any type of code , no check engine light feels normal Knightstale04