Getting a gas smell when the car is filled. Reading others having the same problem. Also found the following article from the NHTSa.
http://www.detroitnews.com/story/business/autos/foreign/2014/12/23/mercedes-fuel-lead-probe/20800823/

Is this problem covered under warranty by MB?

Thank you

 

It's covered for the E Class cars but not the C Class as far as I know. I'm guessing your SOL when it comes to having it covered under that extended warranty.

 

We'll that's just great... :-(
Thanks for the reply

 

I did some more checking and found the problem.
The tank seal for the sending unit under the back seat on the driver's side is leaking. You can see and smell evidence of a leak.

Has anyone replaced the seal themselves or is it something that a mechanic should do?
I'm fairly handy with tools and repairs but not all that comfortable when it comes to the fuel system.

From what I'm reading, this seal failure seems to be common in the C Class model. I've read there's a newer seal design that looks bigger.
It's too bad Daimler Benz doesn't warranty this like the tanks on the E Class.. I consider it a bad design or quality issue on their part.

 

I had the same problem...gas smell coming from back seat when filling gas tank. The problem for my vehicle was the tank seals for the sender unit and relay caps were bad. The original seals were small and the new ones are much larger. I got both of them online for $30.00. If you have some mechanical skill, the job can be completed in about 2 hrs. Disconnect negative cable from battery. Remove the back seat and lift the protective plastic to reveal each access panel. Remove the access panels (6 small bolts each). For the sender unit (driver side) unplug both electrical connections, then remove fuel line clamp. Before removing fuel line from sender unit, be aware there is some pressure in the fuel line, so surround the area with rags and then gently twist the fuel line back enough to only let a small ammount of fuel to exit until pressure is released...then remove the line completely. Then use a 1/4 ratchet with small extention to remove a hoseclamp, which holds the cap in place. The cap then pulls apart and slips off. Then pull up the sender unit part way, remove the old seal over the top of the sender unit and replace with the new seal (slipping the new seal into the gas tank, then pushing the sender unit back into place). Slip the retaining ring back into position, re-attach and tighten the hose clamp over the retaining ring, re-attach fuel line with new hose clamp and plug back the electrical connections. Same procedure on passenger side without dealing with fuel or electrical connections, but is under a little tension due to two springs..so lift slowly before removing cap to replace old seal. Also check the cap where the springs attatch for cracks in the plastic...in which case you would have to order a new one. Before doing the procedure, look to see if there is evidence of fuel leakage before ordering parts and wear protective clothing, gloves and eyewear...good luck!

 

Thank you for the detailed information on how to fix the seals.
Can you tell me where online you purchased them?

 

I ordered them at Eeuroparts SKU: 703998800

 

Thank you... I see it's one seal.. is that all you need.. one for each side?

 

203 should be posting here: https://mbworld.org/forums/c-class-w203-3/

Here are instructions fuel pump shown, seal is same for filter (left side) check both (2 in total): https://www.pelicanparts.com/techart...eplacement.htm - OEM part # search 019997234564 or 0199972345.

 

Order two of them...one for each side. Just a couple more things that will make the job easier: If you have the large hoseclamp holding the caps on like mine, buy a flexible extension for your socket set to reach in that small space easier. It was also helpful to use a little WD-40 to help slide the caps into the new seals. They are pretty tight.

 

You might fix it yourself.