Error Code P0446
 

1998 Mercedes C230 - replaced water pump, timing belt...car sounded funny and didn't run right. All brake warning lights came on. Had brakes, rotors and brake sensor replaced. On drive home, car started "shuddering" and stalling. Codes had me replace mass air flow sensor and the adjoining parts. Now I am getting the code P0446. This car has 300,987 miles, does not burn oil AND I am a female who really wants to get another year out it...any suggestions would be greatly appreciated!

Code P0 446 is strickly about the charcoal canister shut-off valve.
That is a part that allows the fuel system to make sure that the gas cap is on.

Would not cause any type of running problem,

That car doesn't have a "timing belt". Does have a belt for the water pump.

Googling the OBDII code name is usually educational. Sounds like you need to go to a shop to get the rest of the codes read.

Most likely a unconnected wire from when you R/R'd the water pump. that or hate to tell you, but not sure if the 98's wiring harnesses had isues or not. If they had issues, I would suspect the harness, as you just moved it all over the place.

A 1998 model shouldn't have wiring harness issues.

I got this in my ML350 and other forums and sources also suggest it has something to do with the charcoal canister. It does not always stay on.