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2003 Silverado Code Po446


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#1 sawdust2

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Posted 24 October 2007 - 08:28 AM

I keep getting code po 446 on my 2003 Silverado. I have read that it could be the vent control valve. Any ideas?
Thanks

#2 M. Cueva

M. Cueva

    M. Cueva

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Posted 24 October 2007 - 08:34 AM

I keep getting code po 446 on my 2003 Silverado. I have read that it could be the vent control valve. Any ideas?
Thanks

I would say that you have to deal with one of these four solutions (Take your pick):

Document ID# 1538679
2003 Chevrolet Chevy C Silverado - 2WD

Subject:03-06-04-037 Supplement - EVAP Canister Installation Information - kw 4.3 4.8 5.3 6.0 8.1 bracket CEL L18 L35 LM4 LM7 LQ9 LQ4 LR4 LU3 MIL P0446 SES vent #PIP3073 - (07/21/2004)

Models:.


The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.


Condition/Concern:
When installing the new EVAP canister mentioned in 03-06-04-037, it may be noted that the new EVAP canister to frame mounting bracket (15175907) does not mount to the EVAP canister like the original bracket.


Recommendation/Instructions:
As installed, the original EVAP canister to frame mounting bracket clamped on a vertical edge EVAP canister and was held to the frame with a bolt. The new EVAP canister to frame mounting bracket clamps to the top, horizontal edge of the EVAP canister and mounts to the frame using the same bolt hole. To install the bracket, line up the locating tab of the bracket with the locating hole in the frame and install the old bolt. Once secure, line up the two flat locating tabs of the bracket with the two female locating holes of EVAP canister and lock it into place. Once the EVAP canister is locked into the frame bracket, secure the other end of the canister like the old canister was and install all of the related EVAP lines.

.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.


Models:
(03 GMC Sierra ) (03 Chevrolet Silverado


AND / OR AND / OR AND / OR AND / OR AND / OR AND / OR AND / OR AND / OR AND / OR


Document ID# 1363022
2003 Chevrolet Chevy C Silverado - 2WD

Subject:Service Engine Soon Light On with DTC P0446 Set (Replace Canister) #03-06-04-037 - (07/31/2003)

Models:2003 Chevrolet Silverado


2003 GMC Sierra


with 4.3L, 4.8L, 5.3L, 6.0L or 8.1L Engine (VINs W, X, V, P, T, N, U, G - RPOs L35, LU3, LR4, LM4, LM7, LQ9, LQ4, L18)



Condition
Some customers may comment on the Service Engine Soon light being illuminated. Upon investigation, the technician will find a DTC P0446, EVAP system blocked or restricted vent path.


Cause
Variation in flow restriction through the EVAP canister may cause the new diagnostic to set the code.


Correction
Check the system operation using the current diagnostics for P0446.

If diagnostics lead you to replace the EVAP Canister or no concerns are found, then replace the EVAP canister and bracket. A new canister has been released with pelletized charcoal instead of powdered charcoal. This allows for a less restricted, more consistent flow through the canister.


Parts Information
Part Number

Description

Qty

15175906

Canister, EVAP

1

15175907

Bracket, EVAP Canister

1

Parts are currently available from GMSPO.


Warranty Information
For vehicles repaired under warranty, use:

Labor Operation

Description

Labor Time

L0620

Canister, Fuel Vapor - Replace

Use Published Labor Time

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
Posted Image WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

Copyright General Motors Corporation. All Rights Reserved.



AND / OR AND / OR AND / OR AND / OR AND / OR AND / OR AND / OR AND / OR AND / OR


Document ID# 1962238
2003 Chevrolet Chevy C Silverado - 2WD

Subject:DTC P0446 (Restricted/Blocked EVAP Vent Path) Set, Service Engine Soon (SES) Lamp Illuminated (Replace Evaporative Emission (EVAP) Vent Valve Solenoid Assembly with Service Kit) #02-06-04-037C - (04/17/2007)

Models:1999-2007 Chevrolet Silverado (Classic) Models


1999-2007 GMC Sierra (Classic) Models


This bulletin is being revised to update the warranty information to include additional labor time for diagnosis. Please discard Corporate Bulletin Number 02-06-04-037B (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.


Correction
After following the Service Information diagnostics for P0446 and determining that the EVAP canister vent valve is the cause of the SES light, replace the existing EVAP canister vent valve assembly with a new assembly. This new assembly is a sealed unit that is designed to be vented through a remote filter box. To ensure correct installation, follow the procedures below.


1999-2003 Model Year (Use Service Kit P/N 19152345)
  • Raise the vehicle. Suitably support the vehicle.
  • Disconnect the EVAP canister vent valve electrical connector, if equipped.
  • Disengage the two vent valve pipe clips securing the pipe to the underbody. Remove the clips from the underbody and discard.
  • Disconnect the vent valve pipe at the EVAP canister.
  • Remove and retain the EVAP canister vent valve bracket mounting bolt.
  • Remove the complete EVAP canister vent valve assembly with bracket attached and discard.
    Posted Image

    Important: The new canister vent valve will be installed in a new location, outside of the frame.
  • Position and secure the new valve assembly to the frame bracket on the outside of the frame using the existing hole and mounting bolt.Tighten
    Tighten the bracket mounting bolt to 12 Nm (106 lb in).
  • Connect the vent valve pipe to the EVAP canister.
  • Install the two vent valve pipe clips into the existing underbody holes.
  • Connect the EVAP canister vent valve electrical connector, if equipped.
  • Attach bulk 5/8" heater hose to the vent valve port and secure using a clamp. Run a length as needed along the frame rail routing to the area above the transmission.
  • Cut the hose to determined length and install the supplied filter box. Secure using a clamp.
    Posted Image
  • Secure the filter box to the fuel lines above the transmission using a tie strap. The filter box opening should be pointing downward.
  • Tie strap the hose as needed along the frame rail in order to keep the hose away from pinch-points and heat sources.
  • Lower the vehicle.
2004-2007 Model Year (Use Service Kit P/N 19152349)
  • Raise the vehicle. Suitably support the vehicle.
  • Disconnect the EVAP canister vent valve electrical connector.
  • Disconnect the canister pipe from the vent valve.
  • Push in the retainer and remove the existing canister vent valve from the fuel tank clip or mounting bracket. Discard the old valve.
  • Cut back the existing canister pipe approximately 51 mm (2 in) to remove the quick connect end.
    Crew Cab Short Box Shown Below, Other Configurations Similar

    Posted Image


    Extended Cab Short Box Shown Below, Other Configurations Similar

    Posted Image
  • Install the new canister vent valve to the fuel tank clip or mounting bracket.
  • Cut bulk 5/8" heater hose to a length of approximately 76 mm (3 in). Install the hose between the vent valve and the canister pipe and secure using clamps.
  • Attach bulk 5/8" heater hose to the vent valve port and secure using a clamp. Run a length as needed along the frame rail routing to the area above the transmission.
  • Cut the hose to determined length and install the supplied filter box. Secure using a clamp.
    Posted Image
  • Secure the filter box to the fuel lines above the transmission using a tie strap. The filter box opening should be pointing downward.
  • Connect the EVAP canister vent valve electrical connector.
  • Tie strap the hose as needed along the frame rail in order to keep the hose away from pinch-points and heat sources.
  • Lower the vehicle.

Parts Information
Part Number

Description

Qty

Material Allowance

19152345 (1999-2003 Model Year)

Solenoid Kit, EVAP Emission Canister Vent Valve

1

--

19152349 (2004-2007 Model Year)

Solenoid Kit, EVAP Emission Canister Vent Valve

1

--

9438383 (5/8" X 25' roll)

Hose

Cut to Length

$10.80 USD ($22.59 CAD)

12337820 (10 per pack)

Tie-Strap

5

$3.80 USD ($4.55 CAD)

15620999 (10 per pack)

Clamp

2 (1999-2003)

or

4 (2004-2007)

$3.78 USD ($7.08 CAD) (1999-2003)

or

$7.56 USD ($14.17 CAD) (2004-2007)

Put unused material on shelf for future use.


Warranty Information
For vehicles repaired under warranty, use:

Labor Operation

Description

Labor Time

J7908*

Solenoid, EVAP Emission Canister Vent Valve - Replace

0.9 hr**

* This is a unique labor operation number for bulletin use only. This number will not be published in the Labor Time Guide.

**Diagnosis time is included in this labor time .



GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
Posted Image WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

Copyright General Motors Corporation. All Rights Reserved.





AND / OR AND / OR AND / OR AND / OR AND / OR AND / OR AND / OR AND / OR AND / OR


Document ID# 2008255
2003 Chevrolet Chevy C Silverado - 2WD

Subject:Service Engine Soon (SES) And DTC P0446 Set - keywords dtc emissions evap evaporative fill filler fuel hard hose lamp light vent #PIT4484 - (08/30/2007)

Models:1999-2008 Chevrolet Silverado, Silverado Classic


1999-2008 GMC Sierra, Sierra Classic


The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.


Condition/Concern:
Some customers whose vehicles are operated in dusty/muddy type environments, such as farming, mining or off-road type applications, may comment about the illumination of the SES light, with a DTC of P0446 (Restricted/Blocked EVAP Vent Path) being set. If bulletin 02-06-04-037B (classic only) was completed for the Silverado/Sierra Classic and on the new body style Silverado/Sierra pickups, the vent solenoid prefilter intake is located at the rear of the transmission. It has been found that even in this location the prefilter may become plugged with dust/mud.


Recommendation/Instructions:
If the prefilter intake is plugged with dust/mud relocate the prefilter forward and additional 8 5/8 inches (220 mm) from its current location, as shown below.


Posted Image

(1) New Location Of PreFilter

(2) Current Location Of PreFilter

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.



GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
Posted Image WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

Copyright General Motors Corporation. All Rights Reserved.







Edited by M. Cueva, 24 October 2007 - 08:36 AM.

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#3 RPOZ28

RPOZ28

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Posted 12 August 2013 - 07:57 PM

Hello everyone! I am dragging up this old topic.My sons "new" truck is an 03 Silverado w/4.8. It is pulling a PO446 trouble code. I am hearing it is a possible vent valve solenoid issue. Believe me I have used the search feature and am more confused now than before. There is a TON of good info on here,but it is almost overload,which is good. I can't find a good picture of what the original valve actually looks like as there  are purge valves and vent valves. I am afraid  to mix up the two. Also,if I am correct, the vent valve has to be updated with a new style???? All the pics show a close up of the new style,but need a good diagramof the update. Lastly,I see many many GM and Delco p/n for this part. What do I specifically need for this year truck as far as part number??? HELP !!.....Thank You all !......BILL



#4 brucelimerick

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Posted 16 August 2013 - 08:34 PM

Hi Bill,

I'm just in the process of repairing a burst brake line and also going to do the vent valve as well.  I have a 2001 Sierra.  Just for your information the TSB-02-06-04-037B is now up to J.  GM obviously has no clue.  From what I can tell from all the BS and when I pulled the tube joining the charcoal canister and the vent valve is mine is probably plugged with dirt.  When I first checked with GM parts a year or 2 ago,  they wanted $35 CA to replace the vent valve and mentioned it needed to be relocated.  I checked this week and they now want $212 CA, I have to lower the transmission, run 5' of 5/8" heater hose from the vent valve to the new filter which apparently is to be located above the transmission under the firewall.  Needless to say GM has been working on this defficient design flaw for 12 years now and who knows if they have figured it out this time.  They have had 9 tries so far, idiots.  Anyway, with all this hassle I have found that several US auto parts companies and NAPA in Canada are carrying this "factory part" for $25 to $48.  And bonus many more like my fan resistors.  Everything minimum 1/2 GM prices from the same manufacturer GM uses.

As I had a burst rear break line, the one that goes between the tank and the box, and reading about the problems of dealing with lowering the gas tank I have pulled the box off my truck and can get you all kinds of photos of what you want.  I have the 2001 vent valve off and will be getting the new kit from NAPA in the morning.  As for the new stupid suggestion from GM I'm going to ignore their new location.  An extra foot or 2 of heater hose won't blow the bank and I figure I will mount the new filter up near the master cylinder where I can keep an eye on it and if I have to repair it I won't have to drop the trany and take half my truck apart to get back at it.

Bruce






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