Check Engine lights give code P0456 (on '03 C230), which is a slight leak from evap system. I keep resetting it and it keeps coming back, even with gas cap srewed in tight. Anybody out there found a solution? I guess I may need to replace my gas cap. How do you remove the cap, or is it possible to just replace a seal or o-ring in the cap? What else should be checked? Hoping folks out there have found a common fix for this one. Thanks.

 

It could be numerous things. I had this code on my 05 C230 and it turned out to be a small leak in the fuel filler neck.

 

I've had/have the code as well:

https://mbworld.org/forums/c-class-w...-cold-cel.html

good luck and let us know what happens

 

Oh! dear - here we go again - could be charcoal canister or cap or a leaking purge valve. I recommend you start with a smoke test of the system under pressure.

 

A smoke test is what it took on my car to diagnose it. This was after they threw a purge valve at it as a guess.

 

How do you do a smoke test? I searched to no avail....

 

Subscribed!

 

had this code happen on monday and took it to the dealer....P0456.....fuel filler neck fitting part was $469....not covered under cpo warrenty...

 

What charcoal canister are you referring to? I just had my CEL come on last night in an 06E55 and this was the code...