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

 

Hello, svtguy08

Welcome to the forum.

First off check your gas cap seal to verify that it is clean and is sealing properly.

If ok, re-tighten it until it clicks a few times, then reset the codes and see if they come back.


P0450 has to do with the Fuel Tank Pressure Sensor - (Ie.. it's detected a leak -- more than likely the gas cap.)

P0446 is the Activated Charcoal Canister -

If tightening the gas cap and clearing the codes does not work, then you may have either a defective Fuel Tank Pressure Sensor or the Activated Charcoal Canister is plugged.

Hope this helps

 

SL600_Cruzin,

Thanks for the reply!! The gas cap on the ML was just replaced by the dealer due to the fact that the check engine light came on and was giving the code P0455. That light went on and off after the new cap and it seemed like the it would come on closer to when the fuel tank was around 1/4 left.
When the light came on this for the codes p0446/p0450, before i plugged the scan tool in i thought the CE light was due due to the problem described above but it was different. It seems like this car if a lot trouble. We have had it for a year now, bought it with 72000 of the odometer and the fuel pump has crapped out, the numerous CE lights and minor interior trim pieces falling off, breaking, coming lose, etc...

Thanks Again!!