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Need second opinion on 2014 silverado with the P0446

Paul Collins
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Paul Collins New Member

Paul Collins

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First post here! Browsed many times over the past 4 years I've had my '14 silverado 1500 and found a lot of good info. Anyways onto my current issue: P0446 code, no specific code for the tank pressure sensor but I believe its malfunctioning making the computer think the vent valve solenoid is shot. 

 

I cant find the range for fuel tank pressure anywhere online, but Mine is constantly pegged at -11.95 to -12.0h2o of vacuum and hovers around 4v. Computer shows vent valve venting, purge solenoid closed. Doesn't matter with gas cap off or on and I also removed the line from the charcoal canister that runs to the tank and blew into it with an air gun, I can hear the air enter the tank and then it vents back to me when I release the air gun but the tank pressure reading literally never moves. Blew air into every port of charcoal canister and it flows thru it fine. 

 

I also have a purge flow monitor test it's showing as failed, I don't believe this to be the purge solenoid its self but I assume the FTP sensor is just tossing bad data at the computer so it thinks the flow is bad? Thanks for any help, just looking for a second opinion I guess, I hate just shooting the parts cannon at stuff and praying it sticks.

 

Edited to remove photos and make it easier to read.

 

 

 

Edited by Paul Collins
Problem solved-updating
tbarn Senior Enthusiast

tbarn

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Key on, engine off, scanner should be around 1.5v. for fuel tank pressure sensor.

Paul Collins New Member

Paul Collins

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Thanks for the reply, makes sense. The entire fuel pump assembly was brand new from AC delco back in march...the old one rotted away and started leaking. Looks like the tanks comin down again at least partially to check wiring and probably replace that sensor. 

Paul Collins New Member

Paul Collins

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Just bumping for an update incase anyone searches this in the future. The fuel tank pressure sensor solved my issue. The moment I unplugged the old one the voltage dropped to 0 as it should, and plugged the new one it it went right to 1.5v and -.3 H2o of vacuum. No more CEL after 5 days or P0446.

 

Also just a heads up, I was able to replace this sensor without dropping the tank or unbolting the bed. I was able to reach over the frame on drivers side in the area the filler hose is, and feel around for the sensor. It pulls out with a little persuasion and patience and the wiring harness is long enough to toss over to the driveshaft side and unplug, and plug the new one in. Toss it back on top of the tank with a little lube on the rubber grommet that wont' deteriorate rubber and push it back in. Took maybe 20 mins. My fuel pump is only 6 months old so all clean metal, not sure how easy it would have gone with my original one that was rotted out and leaking.

 

Thread can die off or be closed now, thanks!

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