6th Gen ('00-'05): P0446?
#1
03-01-2015, 09:25 AM
P0446?
So I get an occasional P0446. In reading here: P0446 Evaporative Emission Control System Incorrect Purge Flow it looks like to replace the "vent valve" first? Where is the vent valve? LOL I have a new gas cap and its on securely so I don't think its a gas cap issue.
I have had this code before and usually when I clear it it doesn't come back for a good long time but I thought I'd try to track it down. What is the most common cause for this code?
I have had this code before and usually when I clear it it doesn't come back for a good long time but I thought I'd try to track it down. What is the most common cause for this code?
#2
03-01-2015, 11:11 AM
Hopefully this helps
Possible causes
- Missing Fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- Vent control valve harness is open or shorted
- Vent control valve circuit poor electrical connection
- Faulty vent control valve
What does this mean?
When is the code detected?
The P0446 codes triggered when an improper voltage signal is sent to Engine Control Module (ECM) through EVAP canister vent control valve.
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Possible a noticeable fuel odor caused by the release of fuel vapors
P0446 Description
The Evaporative System (EVAP) canister vent control valve is located on the EVAP canister and is used to seal the canister vent.
This solenoid valve responds to signals from the Engine Control Module (ECM). When the ECM sends an ON signal, the coil in the solenoid valve is energized. A plunger will then move to seal the canister vent. The ability to seal the vent is necessary for the on board diagnosis of other evaporative emission control system components.This solenoid valve is used only for diagnosis, and usually remains opened.
Read more: P0446 Evaporative Emission Control System Vent Control Circuit Malfunction OBDII Engine Light Trouble Code | Engine-Codes.com
AC/Delco Part Chevy Monte Carlo Vapor Canister Vent Solenoid Valve (with Jumper Harness) - AM Autoparts
Diagram--> FUEL TANK & FILLER PIPE. Fits: Impala, Impala o, Lumina, Monte Carlo | Nalley Buick GMC Brunswick
Possible causes
- Missing Fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- Vent control valve harness is open or shorted
- Vent control valve circuit poor electrical connection
- Faulty vent control valve
What does this mean?When is the code detected?
The P0446 codes triggered when an improper voltage signal is sent to Engine Control Module (ECM) through EVAP canister vent control valve.
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Possible a noticeable fuel odor caused by the release of fuel vapors
P0446 Description
The Evaporative System (EVAP) canister vent control valve is located on the EVAP canister and is used to seal the canister vent.
This solenoid valve responds to signals from the Engine Control Module (ECM). When the ECM sends an ON signal, the coil in the solenoid valve is energized. A plunger will then move to seal the canister vent. The ability to seal the vent is necessary for the on board diagnosis of other evaporative emission control system components.This solenoid valve is used only for diagnosis, and usually remains opened.
Read more: P0446 Evaporative Emission Control System Vent Control Circuit Malfunction OBDII Engine Light Trouble Code | Engine-Codes.com
AC/Delco Part Chevy Monte Carlo Vapor Canister Vent Solenoid Valve (with Jumper Harness) - AM Autoparts
Diagram--> FUEL TANK & FILLER PIPE. Fits: Impala, Impala o, Lumina, Monte Carlo | Nalley Buick GMC Brunswick
#4
03-05-2015, 03:26 PM
Honestly, I would try another gas cap first. I actually had a Grand Prix that had this problem and I bought another new gas cap and it never threw the code again.
Beyond that, I am not really sure what all is required to change out the stuff back there as far as sensors, etc.
Hopefully someone on the forum has actually had to do this procedure and can offer some insight on the procedure.
Beyond that, I am not really sure what all is required to change out the stuff back there as far as sensors, etc.
Hopefully someone on the forum has actually had to do this procedure and can offer some insight on the procedure.
#5
09-09-2015, 07:55 AM
P0446
This post is a few month's old but for anyone who finds it:
Changing the vent valve in the back isn't hard. The rear driver-side wheel well needs to come out, so jack the car up and take off that tire. The wheel well is a flexible plastic held in by a screw to your left (sitting facing the car) and two in front of you. I believe they were 8mm, I forget. To your right, there is a black rivet that will need to be pulled out, and then another larger bolt under neither (same side) Once that is out, look up to your right, you'll see the gas filler neck and another hose. The only other thing up there is the vent valve. It's simply clipped onto a bracket. I found it easier to remove the bracket w/ the canister attached (only one bolt) after disconnecting the wire harness and the hose. unclip the old, slide on the new, bolt the bracket back, connect your hose (I did this before bolting it back on) and wire's and you're done.
Changing the vent valve in the back isn't hard. The rear driver-side wheel well needs to come out, so jack the car up and take off that tire. The wheel well is a flexible plastic held in by a screw to your left (sitting facing the car) and two in front of you. I believe they were 8mm, I forget. To your right, there is a black rivet that will need to be pulled out, and then another larger bolt under neither (same side) Once that is out, look up to your right, you'll see the gas filler neck and another hose. The only other thing up there is the vent valve. It's simply clipped onto a bracket. I found it easier to remove the bracket w/ the canister attached (only one bolt) after disconnecting the wire harness and the hose. unclip the old, slide on the new, bolt the bracket back, connect your hose (I did this before bolting it back on) and wire's and you're done.
#7
11-28-2015, 08:56 AM
UPDATE:. P0446 wasn't the Vent Valve as the code says. Check Engine light came back on about a month later with the same code. Ended up being the Fuel Tank Pressure Sensor. Easy to change, there is a trap door in the trunk. Fold down the back seats and lay in. Fold the carpet back, you'll see it. Might need a screwdriver to pry the cover up, it tends to stick. But be careful, it is thin and can bend. (Won't do any harm, but still.)
Unfortunately, there's no way to test this, but it is cheap. Test the Vent Valve and Purge Solenoid's first. If they both pass, try the FTPS.
Unfortunately, there's no way to test this, but it is cheap. Test the Vent Valve and Purge Solenoid's first. If they both pass, try the FTPS.
#8
11-29-2015, 01:54 PM
This post is a few month's old but for anyone who finds it:
Changing the vent valve in the back isn't hard. The rear driver-side wheel well needs to come out, so jack the car up and take off that tire. The wheel well is a flexible plastic held in by a screw to your left (sitting facing the car) and two in front of you. I believe they were 8mm, I forget. To your right, there is a black rivet that will need to be pulled out, and then another larger bolt under neither (same side) Once that is out, look up to your right, you'll see the gas filler neck and another hose. The only other thing up there is the vent valve. It's simply clipped onto a bracket. I found it easier to remove the bracket w/ the canister attached (only one bolt) after disconnecting the wire harness and the hose. unclip the old, slide on the new, bolt the bracket back, connect your hose (I did this before bolting it back on) and wire's and you're done.
Changing the vent valve in the back isn't hard. The rear driver-side wheel well needs to come out, so jack the car up and take off that tire. The wheel well is a flexible plastic held in by a screw to your left (sitting facing the car) and two in front of you. I believe they were 8mm, I forget. To your right, there is a black rivet that will need to be pulled out, and then another larger bolt under neither (same side) Once that is out, look up to your right, you'll see the gas filler neck and another hose. The only other thing up there is the vent valve. It's simply clipped onto a bracket. I found it easier to remove the bracket w/ the canister attached (only one bolt) after disconnecting the wire harness and the hose. unclip the old, slide on the new, bolt the bracket back, connect your hose (I did this before bolting it back on) and wire's and you're done.
#9
10-16-2016, 12:15 AM
PO300
PO403
PO405
PO446 ✴︎ ⬅︎ ⬅︎ ⬅︎
All these Codes were triggered by a faulty FUEL TANK PRESSURE SENSOR!
Wait for the Low Fuel Warning before attempting to DIY.
Start engine.
Pull FUEL PUMP Relay ... Let Engine stall to relieve pressure in system.
Remove GROUND Wire from Battery.
With car Raised and SAFETY STANDS securely in place.
Support Tank with Jack.
(I made a "Jig" to attach to the Jack. Sawed the square bottom off from Milk Crate. Drilled holes through Hockey Puck. Mounted Puck to center of Milk Crate with Heavy Duty Zip Ties. Affixed carpet to other side of Milk Crate bottom for padding.)
Lower tank enough to access Sensor atop Fuel Pump.
Unfasten Pigtail from Sensor.
Unclip and Remove Sensor ••• Straight-up.
DO NOT BREAK THE END OF SENSOR OFF INSIDE PUMP!!!
If you need a Charcoal Canister do it when you replace Sensor.
Removing Relay to releive Pressure throws a Code which may require a MIL Light reset.
PO403
PO405
PO446 ✴︎ ⬅︎ ⬅︎ ⬅︎
All these Codes were triggered by a faulty FUEL TANK PRESSURE SENSOR!
Wait for the Low Fuel Warning before attempting to DIY.
Start engine.
Pull FUEL PUMP Relay ... Let Engine stall to relieve pressure in system.
Remove GROUND Wire from Battery.
With car Raised and SAFETY STANDS securely in place.
Support Tank with Jack.
(I made a "Jig" to attach to the Jack. Sawed the square bottom off from Milk Crate. Drilled holes through Hockey Puck. Mounted Puck to center of Milk Crate with Heavy Duty Zip Ties. Affixed carpet to other side of Milk Crate bottom for padding.)
Lower tank enough to access Sensor atop Fuel Pump.
Unfasten Pigtail from Sensor.
Unclip and Remove Sensor ••• Straight-up.
DO NOT BREAK THE END OF SENSOR OFF INSIDE PUMP!!!
If you need a Charcoal Canister do it when you replace Sensor.
Removing Relay to releive Pressure throws a Code which may require a MIL Light reset.
#10
02-19-2019, 12:59 PM
I have a 2002 Monte Carlo with 96k I’ve been having problems with the P0446 code going a way but coming right back I need help I change the charcoal canister which one I did had gas in it I change the Pcv Val solenoid the whole hose because it was dry rotted and cracked fuel pump and sending unit which came with a new gas tank pressure sensor and change the vent solenoid checked the hoses change the gas cap but it was a new name gas cap and it was hard to get off every time I filled up and I was gonna wait till spring but I said screw it Because I was starting to get a rough idle when parked at coldstart can I wait like 20 seconds or tap the gas once or twice and it was fine I read up it could be a head gasket or intake gasket but I’m not using any coolant and there’s no mixture in my oil I just cleared the code Again an put a ACDelco has cap will see how it is now and when I change the canister it didn’t look like my gas tank was bad so any questions or any suggestions would be very helpful I looked up on one of these forms and heard that it could be the idle air sensor so I’m going to change that today or tomorrow when ice starts getting warmer out but please help I don’t know what else to do and I don’t have the money to go to a mechanic
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