Has anyone gotten this code? I am not building up pressure is the gas tank ans my husband checked all hoses for kinks, bought a new gas cap, checked fuel pump for pressure, and everything seems fine except there is no pressure in the tank and it is running very sluggish.
Can anyone help with this?
Laresa

 

This is what the Ford shop manual says.......


Continuous Memory Diagnostic Trouble Code (DTC) P0446 or P1450 indicates that Self-Test has detected the Evaporative Emission Control System has excessive fuel tank vacuum. Also, a DTC P0446 indicates a vent control malfunction.

Possible causes:

EVAP canister purge outlet tube (EVAP canister purge valve to EVAP canister) blockages or kinks.
EVAP canister tube (fuel tank to EVAP canister) blockages or kinks.
Fuel vapor elbow on EVAP canister contaminated.
Restricted EVAP canister.
Canister vent (CV) solenoid stuck closed (partially or fully).
Plugged or contaminated CV solenoid filter.
EVAP canister purge valve stuck open.
Fuel filler cap stuck closed (no vacuum relief).
VREF circuit open in fuel tank pressure (FTP) sensor.
Damaged FTP sensor.

Check for kinks or bends in the fuel vapor hoses/tubes (EVAP canister purge outlet tube and EVAP canister tube).
Visually inspect EVAP canister inlet port, CV solenoid filter and canister vent hose assembly for contamination or debris.
Check CV solenoid filter for blockage or contamination.



The common things I've seen are mud in the canister and the canister vent solenoid being shot or the wiring to the canister vent solenoid being torn off. The resistance of the solenoid should be 48-65 ohms.
Hope this helps.

 

Thank you for the info. I will have him ohm the silenoid.
Laresa

 

I have a 97 Expedition 4.6 and this P0446 error code has been haunting me for a long time! I read Racerguy's post, and began to investigate. I'm VERY confident I've fixed my problem, but only time will tell...

I removed the canister assy from the frame. Pretty simple, 2 nuts, a electrical connector to the solenoid, and 1 hose. The solenoid inlet hose is about 6" long with a 90 degree bend at the end. I removed this hose, and removed the rubber boot that fits around the solenoid. Next step was to dissassemble the solenoid. The end opposite the electrical connection is removable. There are small plastic tabs to release the end cap and allow access to the inner workings of the solenoid. Once the end is off, clean it with soap & water, and you will see the filter material, there is also a rubber "check valve" which should be cleaned. On my truck, the filter was so filthy, I didn't even know it was there until I washed it! Next I cleaned the solenoid valve itself. I connected the valve to 12 volts and exercised it back and forth. it was barely moving at all. I blasted it clean w/ compressed air (carefully) and some electrical parts cleaner. Now the solenoid motion was much better. Note: It only moves about 1/8" - 1/4" in & out or so. So, after cleaning all the parts of the solenoid, I re-assembled it. Next I will be clearing the DTC and see what happens!

I'll post my results...
Thanks Racerguy!

Mike

 

I have a 97 Expedition 4.6 and this P0446 error code has been haunting me for a long time! I read Racerguy's post, and began to investigate. I'm VERY confident I've fixed my problem, but only time will tell...

I removed the canister assy from the frame. Pretty simple, 2 nuts, a electrical connector to the solenoid, and 1 hose. The solenoid inlet hose is about 6" long with a 90 degree bend at the end. I removed this hose, and removed the rubber boot that fits around the solenoid. Next step was to dissassemble the solenoid. The end opposite the electrical connection is removable. There are small plastic tabs to release the end cap and allow access to the inner workings of the solenoid. Once the end is off, clean it with soap & water, and you will see the filter material, there is also a rubber "check valve" which should be cleaned. On my truck, the filter was so filthy, I didn't even know it was there until I washed it! Next I cleaned the solenoid valve itself. I connected the valve to 12 volts and exercised it back and forth. it was barely moving at all. I blasted it clean w/ compressed air (carefully) and some electrical parts cleaner. Now the solenoid motion was much better. Note: It only moves about 1/8" - 1/4" in & out or so. So, after cleaning all the parts of the solenoid, I re-assembled it. Next I will be clearing the DTC and see what happens!

I'll post my results...
Thanks Racerguy!

Mike

 

Hi OhmegaMike and welcome

Thanks for the great post. Let us know how you make out.

 

Well, almost 2 months have passed since I performed the service listed in the post above! Still no check engine light! I would consider this problem fixed! Finally! Thanks for the help, and I hope this can save someone else a trip to the dealer... It's really an easy fix...

Mike

 

Thanks OhmegaMike, did the CVS clean this weekend seems to have worked great.

Thanks Again

Wayne

 

Hi Wayne and welcome to the forum

Good to hear that fixed your truck too.