Date registered: May 2009
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P0446 code - Charcoal canister shut-off valve
my wifes 02 ML320 is showing an 0446 code. If I clear it using my scanner the code will reappear right away (2 starts cycles). Performance of the car does not seem to be affected in any way. I have replaced the actual canister shut-off valve itself with no change, and had the vehicle smoke tested which proved there where no system leaks. However it appears that neither the shut-off valve nor the purge valve under the hood seems to be engaging. Both are getting 14-volts on their power wires when measured to chassis ground, and do engage if "chassis" ground is applied to the low side. However I only measure ~10volts between the power wire and its own ground signal wire. Not enough to trigger them I'm guessing. I understand that the ground wire carries the control signal from another module (N3/10???) which I am not sure where is located.
Soooooo, long story short, I hoping for any clues or direction to help solve this mystery. Am I overlooking something obvious? Where might I find this N3/10 module? Other likely culprits? Thanks to all.