2007. What are the probable causes of DTC P0446?

code p 0442 refers to evaporative emission(EVAP) system---small leak detected====causes--hose connections--intake leak--EVAP canister--EVAP canister purge valve
it also refers to --large leak detected====causes fuel cap loose, off---mechanical fault--hose connections---EVAP pressure sensor
code p 0441 refers to EVAP system--incorrect flow detected====causes hoses, intake leak-- EVAP canister purge valve
code p 0446 refers to EVAP system, vent control---circuit malfunction===causes--wiring---EVAP canister purge valve----ECM
if you can remember when the problem started ( after refueling) it may be that the cap is not fitted correctly
it could that in the fixing process , the wiring has not been correctly installed or the problem is the canister purge valve needs attention

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2004 Buick Rainier code p0446:

I'm not sure what part to buy or where to find it. Can't find this answer anywhere online. Please help. This is code p0446 and non other.

code p0446 refers to evaporative emission (EVAP) system-vent control-circuit malfunction===causes --wiring--EVAP canister purge valve--ECM
code p0455 refers to EVAP system-large leak detected===causes --hose connections--intake leak--EVAP canister---EVap canister purge valve
code p0172 refers to system too rich, bank 1===causes intake blocked---EVAP canister purge valve--fuel pressure ---EGR system---injector/s ---ECM
because the EVAP purge valve appears in all codes I would be inclined to change that unit first the run the fault codes again

A loose or wrong type fuel filler cap, a small leak in the vapor line from the gas tank to the charcoal canister, a defective vent valve or purge valve...If you have changed the fuel cap recently, or if you see a defect in yours, replace the cap, erase the codes, and see if driving makes the code come back.

Here is a description and possible other solutions: http://www.obd-codes.com/p0442

P0446 Evaporative Emission Control System Vent Control Circuit Malfunction The code P0446 is set when the engine computer recognizes a fault or restriction at the vent control part of the Evaporative emission control system (EVAP). The description of the fault varies between different car manufacturers, but one thing is common, the code P0446 doesn't directly point to a defective part; some testing might be required to pinpoint the faulty component. What can cause the code P0446: - faulty vent control valve - blockage at the vent hose, vent filter or vent control valve - open or short in the vent control valve circuit - bad charcoal canister - EVAP system leak - faulty EVAP system pressure sensor - bad vacuum switching valve (VSV) - stuck open purge valve (solenoid)

P0446 has nothing to do with the canistor !
DTC P0446 Evaporative Emission (EVAP) Vent System Performance
This DTC tests the evaporative emission (EVAP) system for a restricted or blocked EVAP vent path. The control module commands the EVAP canister purge solenoid valve Open and the EVAP canister vent solenoid valve Closed. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the EVAP canister purge solenoid valve Closed and the EVAP canister vent solenoid valve Open. The control module monitors the fuel tank pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inches H2O in a calibrated time, this DTC sets.
DTC P0452 Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage


How to troubleshoot an EVAP Pressure Sensor problem P0452 GM

EVAP Vent Solenoid Code P0446 The solenoid is stuck open !

P1442 usually gas cap. P1449 usually vent solenoid. P1441 usually always a faulty FTP sensor. Very problematic to Malibu, Grand Am Cavaliers and Aleros. That would be my first area to check. They are also known for poor wiring connections at the Left rear passthru connector to the fuel tank and vent solenoid, but not necessarily for that code.

Some might have an ses p0446, evap emissions vent circuit low. If you take it to the dealer they want 300-400.00 to fix the problem. GM has a service bulletin on this condition and have the updated part for 180.00, thats suppose to eliminate this issue.

Basically the problem is, the evap purge vent valve gets clogged with dirt, especially if the truck is used in dirty conditions. Well I figured there had to be a cheaper way to cure this problem.

Here it is:
1) find the location of the vent valve; its under the truck, locate the charcoal canister on the front of the gas tank and trace the vent line to the vent valve.
2) Take the bracket loose with a 5/8 wrench.
3) Spin the valve around so the side with the hole is facing you.
4) Take an air compressor and blow the vent valve out.
5) reinstall and clear the code and it's fixed.

Now I know the updated part from gm is supposed to keep the valve from clogging ever again, but why spend the money when all you have to do is blow out the vent valve every 50k-100kmi and save your $$$!

Subject: DTC P0446 (Restricted/Blocked EVAP Vent Path) Set, Service Engine Soon (SES) Lamp Illuminated (Replace Hose/Evaporative Emission (EVAP) Canister Vent Asm) #02-06-04-037A - (02/02/2005)
Models:
- 1999-2003 Chevrolet Silverado Models
- 1999-2003 GMC Sierra Models
--------------------------------------------------------------------------------
This bulletin is being revised to add model years. Please discard Corporate Bulletin Number 02-06-04-037 (Section 06 -- Engine/Propulsion System).
--------------------------------------------------------------------------------
Condition
Some customers whose vehicles are operated in dusty type environments, such as farming or mining off-road type applications, may comment about the illumination of the instrument panel SES light, with a DTC of P0446 (Restricted/Blocked EVAP Vent Path) being set.

Cause
Dirt and dust intrusion into the EVAP canister vent hose assembly, resulting in restricted air flow, may cause this condition.

Part Number 15086429 Hose Asm-Evap Emis Cnstr Vent


Removal & Installation
Purge Solenoid Valve-2.2L (L61) Engine

1. Disconnect the evaporative emission (EVAP) canister purge valve harness connector.
2. Disconnect the vacuum pipe from the EVAP canister purge valve.
3. Disconnect the purge pipe from the EVAP canister purge valve.
4. Remove the EVAP canister purge valve and bracket.
5. Remove the EVAP canister purge valve from the purge bracket.
6. Inspect for carbon release in the EVAP canister purge valve ports.
   

To install:

1. Install the EVAP canister purge valve on to the purge bracket.
2. Install the EVAP canister purge valve and bracket. Tighten the purge bracket nut to 71 inch lbs. (8 Nm).
3. Connect the purge pipe to the EVAP canister purge valve.
4. Connect the vacuum pipe to the EVAP canister purge valve.
5. Connect the EVAP canister purge valve harness connector.
6. Remove the air cleaner outlet resonator.
7. Disconnect the EVAP canister purge valve harness connector.
8. Disconnect the engine purge pipe from the EVAP canister purge valve.
9. Disconnect the engine vacuum pipe from the EVAP canister purge valve.
10. Remove the EVAP canister purge valve mounting bracket attaching bolt.
11. Remove the EVAP canister purge valve along with the mounting bracket.
12. Installation is the reverse of the removal procedure. Tighten the bracket bolts to 71 inch lbs. (8 Nm).

Purge Solenoid Valve-2.4L Engines

1. Remove the front purge pipe from the evaporative emission (EVAP) canister purge valve.
2. Remove the rear purge pipe from the EVAP canister purge valve.
   NOTE The EVAP canister may have released carbon particles, which caused this part to fail, and may cause damage to other components. Check the EVAP canister for loose carbon before returning the vehicle to service.
   
3. Disconnect the EVAP canister purge valve electrical connector.
4. Insert a screwdriver between the EVAP canister purge valve and the mounting bracket in order to release the lock tab.
5. Remove the EVAP canister purge valve mounting bracket attaching nut, if replacing the bracket.
6. Remove the bracket.
   

To install:

1. Install the mounting bracket and the attaching nut for the EVAP canister purge valve. Tighten the nut to 71 inch lbs. (8 Nm).
2. Slide the EVAP canister purge valve onto the mounting bracket. Make sure the lock tab locks the valve in place.
3. Connect the EVAP canister purge valve electrical connector.
4. Connect the rear purge pipe to the EVAP canister purge valve.
5. Connect the front purge pipe to the EVAP canister purge valve.

Vent Solenoid Valve-2.2L & 2.4L Engines

1. Raise the vehicle
2. Loosen the EVAP canister vent valve hose clamp and slide the clamp down the hose away from the EVAP vent valve hose connection.
3. Remove the hose from the EVAP canister vent valve.
4. Remove the EVAP canister vent valve by placing a pry bar between the valve and mounting surface, and moving the valve forward.
5. Remove the clip from the EVAP canister vent valve harness connector
6. Disconnect the EVAP canister vent valve harness connector.
   

To install:

1. Connect the EVAP canister vent valve harness connector
2. Install the clip into the EVAP canister vent valve harness connector.
3. Install the EVAP canister vent valve by pushing the mounts into the original holes.
4. Lubricate the hose end with lubricant.
5. Install the hose to the EVAP canister vent valve.
6. Slide the EVAP canister vent valve hose clamp down on to the hose connection at the EVAP canister vent valve.
7. Lower the vehicle.

Hope this help (remember commetn and rated this).

A. Diagnostics for PO441:

1. Remove Vacuum Hoses between EVAP VSV and Charcoal Canister and discard.
2. If there is a metal vapor pipe between EVAP VSV and Charcoal Canister, clean inside of vapor
pipe
3. Replace EVAP VSV and Charcoal Canister assembly with new parts.
4. Install new vacuum hoses between EVAP VSV and Charcoal Canister.


B. Diagnostics for P0446:

1. Inspect vacuum hoses and pipes between EVAP (Purge) VSV and Charcoal Canister for leaks.
2. Replace Vapor Pressure VSV and Canister.
NOTE :When performing diagnostics for an occurrence of a MIL "ON" condition, Diagnostic
Trouble Code (DTC) P0441 may be result of debris in Evaporative Emission Control System. This
may cause blockage of a vapor line, or a stuck VSV, as described in troubleshooting area of Repair
Manual.

Robert