ML320 with check engine light & codes P0450 P0446
 

Hello all. This is my first post and it is in regards to our family's ML320. It currently has a check engine light on and the codes that I read with my scanner were P0446 and P0450.
Now i know what their definition but im not aware as to what the problem might be or were the problem is located.
Any help would be appreciated! Thanks
P.S. The ML has 88,000 miles and a new fuel pump assembley was just installed.
P0446 - Evaporative Emission Control System Vent Control Circuit Malfunction
P0450 - Evaporative Emission Control System Pressure Sensor Malfunction

P0 446 is an electrical malfunction of the charcoal cannister shut-off valve.
P0 460 is an electrical malfunction of the evaporative system MAP sensor.

The only thing they share in common it the power supply.(12V)

M.B.DOC,

Thanks for the more detailed description of the codes. My question to you and anyone else is, are CC shut-off valve and the EVAP MAP sensor easy parts to replace? Where would they be located? Thanks

The shut-off valve is next to the spare tire mounted on the charcoal cannister section of the fuel tank.


The map sensor is mounted on the fuel filler neck, inside the truck.

Neither part is $$$ but you should check to see if there is power to each of them with key on.