How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Bob Your Own Question

Bob
Bob, Auto Tech
Category: Chevy
Satisfied Customers: 4087
Experience:  Plus 40 years GM, over 30 certified with Chevrolet, ASE certified Master Tech. (Expired, Retired)
Type Your Chevy Question Here...
Bob is online now
A new question is answered every 9 seconds

I have a code PO446 Evap emission control system ...

Resolved Question:

I have a code PO446 Evap emission control system vent circuit malf, this is on my 04 GMC 2500hd with 6.0L. What is the cause of this and how do you repair it ?
Submitted: 5 years ago.
Category: Chevy
Expert:  Bob replied 5 years ago.

This code refers to a problem with the evaporation system on your truck. GM has issued a technical bulletin on it for repairs. I will post a copy of it for you. Thanks

 

#02-06-04-037D: DTC P0446 (Restricted/Blocked Evap Vent Path) Set, Check Engine Light On (Replace Evaporative Emission (EVAP) Vent Valve Solenoid Assembly and Add/Relocate Filter Box Using Service Kit) - (Apr 16, 2008)

Subject:DTC P0446 (Restricted/Blocked EVAP Vent Path) Set, Check Engine Light On (Replace Evaporative Emission (EVAP) Vent Valve Solenoid Assembly and Add/Relocate Filter Box Using Service Kit)

Models:1999-2007 Chevrolet Silverado (Classic) Models
1999-2007 GMC Sierra (Classic) Models
2007-2008 Chevrolet Silverado Models
2007-2008 GMC Sierra Models



This bulletin is being revised to add new style pickups to the models and update the correction information to include a new location for the filter box. Please discard Corporate Bulletin Number 02-06-04-037C (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 check engine 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 (1999-2007 Classic/Old Style Models)

After following the published SI diagnostics for P0446 and determining that the EVAP canister vent valve is the cause of the MIL 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)

  1. Raise the vehicle. Suitably support the vehicle.
  2. Disconnect the EVAP canister vent valve electrical connector, if equipped.
  3. Disengage the two vent valve pipe clips securing the pipe to the underbody. Remove the clips from the underbody and discard.
  4. Disconnect the vent valve pipe at the EVAP canister.
  5. Remove and retain the EVAP canister vent valve bracket mounting bolt.
  6. Remove the complete EVAP canister vent valve assembly with bracket attached and discard.
    Object Number:(NNN) NNN-NNNN Size: SH

    Important: The new canister vent valve will be installed in a new location, outside of the frame.

  7. 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 N·m (106 lb in).

  8. Connect the vent valve pipe to the EVAP canister.
  9. Install the two vent valve pipe clips into the existing underbody holes.
  10. Connect the EVAP canister vent valve electrical connector, if equipped.
  11. 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.
  12. Cut the hose to determined length and install the supplied filter box. Secure using a clamp.
  13. Remove the transmission support and lower the transmission assembly as necessary to allow for access to the new filter box location.
    Object Number:(NNN) NNN-NNNN Size: SH

  14. Secure the filter box to the transmission vent hose just forward of the hose tee-section using a tie strap. DO NOT pinch or restrict the transmission vent hose. The filter box opening should be pointing downward.
  15. Raise the transmission and reinstall the transmission support.
  16. Tie strap the hose as needed along the frame rail in order to keep the hose away from pinch-points and heat sources.
  17. Lower the vehicle.

2004-2007 Model Year (Use Service Kit P/N 19152349)

  1. Raise the vehicle. Suitably support the vehicle.
  2. Disconnect the EVAP canister vent valve electrical connector.
  3. Disconnect the canister pipe from the vent valve.
  4. Push in the retainer and remove the existing canister vent valve from the fuel tank clip or mounting bracket. Discard the old valve.
  5. 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


    Object Number:(NNN) NNN-NNNN Size: SH

    Extended Cab Short Box Shown Below, Other Configurations Similar


    Object Number:(NNN) NNN-NNNN Size: SH
  6. Install the new canister vent valve to the fuel tank clip or mounting bracket.
  7. 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.
  8. 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.
  9. Cut the hose to determined length and install the supplied filter box. Secure using a clamp.
  10. Remove the transmission support and lower the transmission assembly as necessary to allow for access to the new filter box location.
    Object Number:(NNN) NNN-NNNN Size: SH

  11. Secure the filter box to the transmission vent hose just forward of the hose tee-section using a tie strap. DO NOT pinch or restrict the transmission vent hose. The filter box opening should be pointing downward.
  12. Raise the transmission and reinstall the transmission support.
  13. Connect the EVAP canister vent valve electrical connector.
  14. Tie strap the hose as needed along the frame rail in order to keep the hose away from pinch-points and heat sources.
  15. Lower the vehicle.

Correction (2007-2008 New Style Models)

After following the published SI diagnostics for P0446 and determining that the EVAP canister vent valve is the cause of the MIL light, replace the EVAP canister vent valve assembly and relocate the remote filter box. To ensure correct installation, follow the procedures below.

Use Service Kit P/N 19152349

  1. Raise the vehicle. Suitably support the vehicle.
  2. Disconnect the EVAP canister vent valve electrical connector.
  3. Disconnect the vent valve pipe quick connect from the canister.
  4. Either cut the existing valve vent pipe and leave the remaining section of pipe in the vehicle or remove along with the valve.
  5. Push in the retainer and remove the existing canister vent valve from the fuel tank clip or mounting bracket.
  6. Cut back the existing canister pipe approximately 51 mm (2 in) and retain the pipe for use with new valve.
  7. Connect the canister pipe quick connect to the canister.

    2500 Crew Cab Short Box Shown Below, Other Configurations Similar


    Object Number:(NNN) NNN-NNNN Size: SH

    1500 Extended Cab Short Box Shown Below, Other Configurations Similar


    Object Number:(NNN) NNN-NNNN Size: SH

  8. Install the new canister vent valve to the fuel tank clip or mounting bracket.
  9. 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.
  10. 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 passenger side area above the transmission.
  11. Cut the hose to determined length and install the supplied filter box. Secure using a clamp.
  12. Remove the transmission heat shield, if necessary.
  13. Remove the transmission support and lower the transmission assembly as necessary to allow for access to the new filter box location.
    Object Number:(NNN) NNN-NNNN Size: SH

  14. Secure the filter box to the transmission vent hose just forward of the hose tee-section using a tie strap. DO NOT pinch or restrict the transmission vent hose. The filter box opening should be pointing downward.
  15. Raise the transmission and reinstall the transmission support.
  16. Reinstall the transmission heat shield.
  17. Connect the EVAP canister vent valve electrical connector.
  18. Tie strap the hose as needed along the frame rail in order to keep the hose away from pinch-points and heat sources.
  19. 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 (2004-2008 Model Year)

Solenoid Kit, EVAP Emission Canister Vent Valve

1

--

(NNN) NNN-NNNN(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 (2004-2008)

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

or

$7.56 USD ($14.17 CAD) (2004-2008)

Bob, Auto Tech
Category: Chevy
Satisfied Customers: 4087
Experience: Plus 40 years GM, over 30 certified with Chevrolet, ASE certified Master Tech. (Expired, Retired)
Bob and 4 other Chevy Specialists are ready to help you

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
< Last | Next >
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
 
 
 

Meet The Experts:

 
 
 
  • Tim's Auto Repair's Avatar

    Tim's Auto Repair

    mechanic

    Satisfied Customers:

    7497
    Have owned a repair shop for 25 yrs.
< Last | Next >
  • http://ww2.justanswer.com/uploads/TI/tim37857/2011-10-28_23053_S6301814.64x64.JPG Tim's Auto Repair's Avatar

    Tim's Auto Repair

    mechanic

    Satisfied Customers:

    7497
    Have owned a repair shop for 25 yrs.
  • http://ww2.justanswer.com/uploads/DT/dt69nova/2012-6-15_234154_pic1.64x64.jpg Dave Nova's Avatar

    Dave Nova

    Chevrolet Technician

    Satisfied Customers:

    6863
    ASE Master Certification. GM World Class Certification
  • http://ww2.justanswer.com/uploads/ggrote1/2009-06-27_031011_me.jpg Gary's Avatar

    Gary

    Chevy Technician

    Satisfied Customers:

    4944
    15 years GM master tech
  • http://ww2.justanswer.com/uploads/testedtuff/2009-09-26_170108_pictures.jpg John's Avatar

    John

    Master A.S.E Automotive technician

    Satisfied Customers:

    4071
    A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
  • http://ww2.justanswer.com/uploads/RO/rodcuda/2011-7-25_224114_Donhoff1.64x64.JPG Neal's Avatar

    Neal

    Chevy Mechanic

    Satisfied Customers:

    2306
    Shop Owner and Mechanic on multiple makes.
  • http://ww2.justanswer.com/uploads/goodwrench9124/2008-11-09_220838_dscf0007.jpg goodwrench9124's Avatar

    goodwrench9124

    ASE Certified Technician

    Satisfied Customers:

    2041
    Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
  • http://ww2.justanswer.com/uploads/DR/drivefast1971/2012-1-12_172422_0009051tQKh.64x64.jpg Ron Z.'s Avatar

    Ron Z.

    - Chevy Tech -

    Satisfied Customers:

    1813
    18+yrs experience. State Inspector and Chevy Diagnostics