2000 Silverado 5.3l Ses P0446

[JackalAR]

55k mi. Threw code, cleaned vent valve and blew out 5/8" vaccum line, checked the other two vaccum lines going to charcoal box. SES (same code) came back a week later so I replaced the vent valve with the new style large one and cleaned the purge valve. Code came back yet again so I replaced the purge valve and gas cap. All 3 lines coming from the charcoal filter box are clear. The charcoal box doesn't dump any dust out when you hold it with ports down and beat on it...seems to be relatively free flowing, but the line that runs to the fuel tank showed MINOR signs of dust contamination on the end. If the code comes back again, I will replace the box...failing that I'm at a loss. Ideas? Thanks.

[JackalAR]

Bump.

[jro909]

its not the end of the world if you don't fix it, i know somebody thats had the problem since 20k miles and to this day the truck still runs like a champ...p.s the dealer declinded to fix it so she lived with it...

[JackalAR]

Bump.

[JackalAR]

Well, after about 5 tanks of gas, the SES is back. Just wondering what the odds are that it could be the charcoal filter box...???

[rmck490]

On a guess, fuel tank pressure sensor.

 

Did you do anything with the fuel tank pressure sensor? When I got this code, I cleaned the contacts to the sensor connector on top of the tank and the code hasn't returned after 10 or more tank fillups.

[JackalAR]

I haven't touched the FTPS...easily accessible?

[minibike132]

comment removed, bulliten referenced was for a different engine.

[minibike132]

 

On a guess, fuel tank pressure sensor.

[rmck490]

I haven't touched the FTPS...easily accessible?

 

The FTPS is part of the fuel sender/fuel pump assembly accessible on top of the tank. Easiest access is to lift the truck bed on the driver's side. It will be the connector with three wires. An open ground circuit (black wire) to the FTPS can set the P0446 code so check that out. You should find continuity between the frame and the black wire to the FTPS if the ground circuit is closed.

 

I cleaned the contacts to the FTPS with electical spray cleaner and it worked for me. It may not work for you but it's worth a try rather than throwing another part at the problem.