I have a 2002 ML320 suv. The CEL is on, and the code is P0446. It states that there is something wrong with the evap. system circuit, specifically at the charcoal canister shut-off valve.

I've tried literally everything, (replacing valve, checking the wires, resetting the CEL, etc). But it is still on. I don't think there is a leak anywhere in the evap. system, because this code isn't talking about leaks. So I think the last thing to do now is to check the entire evap. system circuit and check for any loose connections, broken wires.

Does anyone know where I can find a diagram of all the wires of the circuit and where they are located throughout the vehicle?

This is a very time-consuming CEL, and if I take it to the dealer, God knows how much money I'll end up paying.

1 Answer 1


This code can also come up from a faulty fuel filler cap gasket or vacuum leak in the soft evap system hoses.
In my experience I had both at separate times. The hoses at the front center of the engine degraded from heat and time.
In both cases simply replacing the parts solved the problem.

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