Joined Aug 2008
L8: Grand Teacher
Forum Thread
Car help - 2006 Monte Carlo error code P0446
April 24, 2021 at
08:02 PM
So wifey inherited this car and a error code is preventing it passing its emissions test which means she can't get it registered.
The Error code is P0446 with the message "Evaporative Emission System Vent Control Circuit".
I tested the purge and vent solenoid and they both seem fine. When i blew harder into the vent solenoid, applied power so that it closed the valve and then removed the power it stayed stuck in the closed position, but i purchased a new unit and it did the same thing so i'm guessing its supposed to act like that. If i don't blow hard, it opens and closes just fine.
Gas cap has also been replaced.
Other info that may be relevant is that i was originally keeping the gas level between half and 3/4 tanks gas as i had reset the code after replacing the gas cap and had to take it through drive cycles and this was recommended. I had no issue when i was putting gas in. But when the check engine light came back on, i didn't worry about maintaining that gas level and when it got low i went to refill it and the handle kept triggering like it was full but the tank was only 1/2 full.
Based on that, i'm thinking the issue is a blockage v's a leak in some part of the system. I don't believe i can access the charcoal canister on this vehicle as i think its above the gas tank - can't seem to find a diagram for its exact location but i'm going to jack up the car and take a closer look around there.
And i'm not sure if its related, but when i run a I/M readiness scan, i was never able to get the CAT or EVAP to go green, and i had a Pd DTC 1 code.
There was no other codes on the scan, although it did just trigger the P0449 which i believe is because i had previously disconnected the vent solenoid.
Any thoughts/suggestions before i take it to a mechanic to have looked over and fixed?
The Error code is P0446 with the message "Evaporative Emission System Vent Control Circuit".
I tested the purge and vent solenoid and they both seem fine. When i blew harder into the vent solenoid, applied power so that it closed the valve and then removed the power it stayed stuck in the closed position, but i purchased a new unit and it did the same thing so i'm guessing its supposed to act like that. If i don't blow hard, it opens and closes just fine.
Gas cap has also been replaced.
Other info that may be relevant is that i was originally keeping the gas level between half and 3/4 tanks gas as i had reset the code after replacing the gas cap and had to take it through drive cycles and this was recommended. I had no issue when i was putting gas in. But when the check engine light came back on, i didn't worry about maintaining that gas level and when it got low i went to refill it and the handle kept triggering like it was full but the tank was only 1/2 full.
Based on that, i'm thinking the issue is a blockage v's a leak in some part of the system. I don't believe i can access the charcoal canister on this vehicle as i think its above the gas tank - can't seem to find a diagram for its exact location but i'm going to jack up the car and take a closer look around there.
And i'm not sure if its related, but when i run a I/M readiness scan, i was never able to get the CAT or EVAP to go green, and i had a Pd DTC 1 code.
There was no other codes on the scan, although it did just trigger the P0449 which i believe is because i had previously disconnected the vent solenoid.
Any thoughts/suggestions before i take it to a mechanic to have looked over and fixed?
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You just need to replace this part, and you'll be good to go.
https://www.oreillyauto
https://repairpal.com/obd-ii-code...alfuncti
wonder if 2004 is the same?
https://www.2carpros.co
https://montecarloforum
This is probably very close
https://www.youtube.com/watch?v=A...han
If you an OBD scanner you should be able to reset the code to go out.
https://repairpal.com/obd-ii-code...alfuncti
wonder if 2004 is the same?
https://www.2carpros.co
https://montecarloforum
This is probably very close
https://www.youtube.com/watch?v=A...han
If you an OBD scanner you should be able to reset the code to go out.
When i first started looking at this, i noticed the gas cap wasn't screwed on properly so i thought that was the cause. I changed it out anyway because wifey didn't want a gas cap with a key on it. I reset the codes after that, and the code came back so that wasn't it.
The link you sent for the diagram is for the vent solenoid, not the charcoal canister. I've tested the vent solenoid and it appears to be working correctly. I did have one concern when i blew harder into it but i got a new one and did the same test and the same thing happened so i guess thats how its supposed to act.
So now i'm confused as to what would have stopped the gas from pumping. I assumed this was part of whatever was causing the CEL code. My only assumption is that the vent solenoid was in the closed position at the time.
From what I have read it is rare for a bad cannister to actually send a code vs the solenoid or a vacuum leak?
this guy here had charcoal chunks in his manifold and no error codes?
https://www.camaroz28.c
Might just want to bite the bullet and take it to a local shop.
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Theres no way for me to check the line or charcoal canister directly because of where the line runs and i believe the charcoal canister sits above the fuel tank. The only other way i can think of to test if there is a blockage is to block off the hose at the vent solenoid, let it sit, and if it sounds like pressure releasing when i remove the blockage i know its passing through. But with the blowing test i'm not sure thats necessary.
Somebody in a Monte Carlo online forum said they had this same code for 3 years even after changing all the parts that could have caused the problem. They added Lucas Oil Deep Clean to their gas and a few days later the CEL dropped. Seems odd, but its not going to hurt to try.
If this fails, off to the shop it goes. I believe i've done everything i can at this point.