I do not know how to close a gas cap....
 

I bought a c230K 2000 recenetly, which had the fuel indicator light and check engine light come on after 10mins of driving. The dealer I bought it from diagnosed it and got a code P0455. I bought a new cap and the problem went away. I drove to work and back 20min each way and never had the light come on, for 4 days in a row. The fuel level was below quarter line.

Today I filled up the tank. I drove about 156KM (distance) and then around 160KM (distance) the light came on again. I stopped and adjusted the cap, then 5 mins later both fuel and CE lights came on.

When I take the cap off, I can see a little bit of gas residue on the cap and I see some wetness on the mouth of the openning. Is this normal?

Also, when I turn the cap ON, it clicks into place, should I stop there or keep turning it untill it can't turn any more?


Thx

Very rarely is this code set by either a bad cap or installing the cap incorrectly. Usually it is another component of the evaporative emissions system such as the shutoff valve or charcoal canister. If they found the code and immediately said you need a new cap, then I'd claim a probably misdiagnosis.
Gilly

What is the proper name for a Charcol Canister?

I think Charcoal Canister is correct. Can't think of what an alternate name would be. It contains activated charcoal and absorbs gas vapors instead of letting it waft off into the atmosphere. Activated Charcoal Canister? One problem in auto mechanics is different people use different names for the same thing. I think Charcoal Canister is correct.
Gilly

Is it true that if this Canister is clogged, its difficult to fill the tank with gas? Because I remember the first time I tried to fill up gas it coughed up over my hands. But since then I drop the nozzle the way inside and fills up just fine.

Is the Fuel Shut off valve a different part than the Charcol Canister Shut off Valve?

The charcoal canister should never "fill" and also I don't believe it would affect the fuelling of the car.
The location of the shutoff valve does vary from model to model, on your C230 I believe it is at a seperate location.
Gilly