04 silverado P0446 low idle

P0446 is a code for the EVAP vent valve . This part is under the vehicle near the fuel tank , not on the fire wall . That is the purge valve .
P0446 Ford EVAP System Vent Control Circuit
Repair Ford Escape P0446 EVAP Vent Problem

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

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)

Quick fix for code p0446 evap emissions vent circuit low.

As the title says: 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 $$$!

as to abs your problem can be the hub itself not the sensor or even problem with abs control have it read to pinpoint problem most auto shops offer this service for free ---as to your 446 code the solenoid is not the only problem need to check the other possible not just change a part the following links should help you may fix problem by blowing out vent hose but sometimes its to late and the canister is filled with dirt [the hose is mounted up in rear wheel well where tires kick up all dirt and dust causing clogging ]
P0446 Chevrolet Evaporative Emission Vent System Performance Quick fix for code p0446 evap emissions vent circuit low P0446 Chevrolet Evaporative Emission Vent System Performance

Well code 446 is for a problem with the EVAP system which vents fumes from the gas tank to the vapor canister.
You would need to check the system using a test chart for that code.
You can look online for the test procedure and the equipment required.

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 !

Please select the link below to further research this particular issue.http://www.gmtruckclub.com/forum/showthread.php/18964-Quick-fix-for-code-p0446-evap-emissions-vent-circuit-low.
orhttp://www.google.com/#hl=en&sugexp=pfwl&cp=42&gs_id=1v&xhr=t&q=+code+p0446+on+a+2001+cheve+silverado+1500&pq=code+p0446+chevy&pf=p&sclient=psy-ab&source=hp&pbx=1&oq=+code+p0446+on+a+2001+cheve+silverado+1500&aq=f&aqi=&aql=&gs_sm=&gs_upl=&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=37320e696dd5b6f0&biw=1360&bih=603&bs=1

Please let me know if you need further assistance. From what I have read from these sites it is a valve or a sensor.

P0446 - Evaporative Emmission Control System Vent Control Circuit

Evap vent valve has only one purpose. It closes in order to seal the vent so the EVAP system can pressurize and ensure there are no leaks. Evap vent valve is usually supplied Batt. voltage with key on. The ECM's driver controls the ground, and when grounded, activates the valve (closing it). If the ECM detects a short to ground, and open,or a short to battery voltage on the control circuit, P0446 will set. Code also may refer to ECM detecting that EVAP system is unable to achieve or maintain vacuum during test.

Causes: A code P0446 could mean one or more of the following has happened:
* Faulty vent valve
* Open, short or excessive resistance on Vent valve control circuit
* Blockage of vent valve
* Bad PCM

Possible Solutions: With a P0446 OBD-II trouble code, here are some things to try:
* Replace Vent valve
* Repair open, short, or resistance problem in control circuit
* Repair open, or short, or resistance problem in power circuit
* Replace PCM

I hioe this helps to solve it.

I had the problem with my 04 silverado odometer malfunction. There was a recall for this model and year. Took it to the dealer had it fixed for free, you need a new odometer replaced but it only covers warany for 7yrs or 75K miles then its prorated.