2004 Yukon Denali. Truck would have a hard time starting after filling tank, changed the purge valve with oem and now it starts perfect after filling, but this code pops up now once in a blue moon. Truck also sometimes makes the pump click off and I have to mess with it about 1/2 the time, but this happened before it would hard start as well and never through a code. In this code a generic evap code? I thought it was specific to the purge valve what else could be bad? Thanks
P0446 after purge valve replaced
- Thread starter Tf79
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
S33k3r
Full Access Member
I'm guessing you have pellets in the system from the charcoal canister. This could also be a failing fuel pump. I'd start with running compressed air through the fuel lines, after disconnecting both ends first, of course.
You could also use an advanced code reader to check your fuel line pressure.
The fuel system needs to be able to get air into and out of the system and deliver fuel at pressure to the engine. The charcoal canister is to trap gas vapors when there is too much pressure in the gas tank and so air is vented to the atmosphere. You've already replaced the purge valve, all the rest of the fun is now at or near the gas tank. Good luck.
You could also use an advanced code reader to check your fuel line pressure.
The fuel system needs to be able to get air into and out of the system and deliver fuel at pressure to the engine. The charcoal canister is to trap gas vapors when there is too much pressure in the gas tank and so air is vented to the atmosphere. You've already replaced the purge valve, all the rest of the fun is now at or near the gas tank. Good luck.
P0446 is an indicator of a problem in the VENT valve, which is under the body in the rear of the truck. Your hard starting could have been caused by the PURGE valve on the engine, so that's worth the new part. Cheap and easy, anyway.
The vent valve in the rear can malfunction; normally it's "open" and should be when fueling (key off, engine off), allowing air out that's been treated by the canister. It's likely that valve, or like @S33k3r notes, perhaps the canister is shot or the evap lines are clogged due to overfilling the tank. I'd probably try a new vent valve before changing the canister, but some people like to replace the three parts and inspect the evap lines to see if charcoal has migrated into the lines.
The vent valve in the rear can malfunction; normally it's "open" and should be when fueling (key off, engine off), allowing air out that's been treated by the canister. It's likely that valve, or like @S33k3r notes, perhaps the canister is shot or the evap lines are clogged due to overfilling the tank. I'd probably try a new vent valve before changing the canister, but some people like to replace the three parts and inspect the evap lines to see if charcoal has migrated into the lines.
nonickatall
Full Access Member
If your vent valve fails, the code pops out of the blue, because the system is only checked at certain conditions. When I remember correctly only when 2/3 filled.
Can fail electricly or due clocked because of charcoal like said before...
Can fail electricly or due clocked because of charcoal like said before...
