[culp71]

good day all,

I just had the CEL come on, on my 2106 gmc canyon 4 wd 2.5l extended can pickup. just turned over 100k
been good all along other then a reprogram for an idle shutter at stops, intermediately, a few other maintenance things,
and a rear water outlet on the block/head that was leaking at temp sensor and hoses that I replaced.
I baby the hell out of this thing as I worked long and hard to save up to buy new with cash.

Its been awesome all along but just about 1 week ago,
about 0 degrees out driving for about 1/2 hour then the CEL came on:
ran no different. no smell of fuel.
got home scanned and codes came up as:
P0448 Evaporative Emission Control System Vent Control Circuit Shorted
P0449 Evaporative Emission Control System Vent Valve/Solenoid Circuit

so I checked the fuse under hood for EVAP canister vent, fine.
I checked electrical connection plug to the canister vent, fine
replaced vapor canister purge valve under the hood
replaced canister vent valve solenoid
check over lines to and from tank, canister, and engine best I could without removing tank
replaced fuel cap
removed and checked over canister for any cracks leaks and all connections etc.
cleaned canister filter foam

I can reset the light, with my scanner but as soon as I turn truck off and restart the CEL doesn't turn off after start up like it normally would but remains on, when i scan I get the same two codes over and over :
P0448 Evaporative Emission Control System Vent Control Circuit Shorted
P0449 Evaporative Emission Control System Vent Valve/Solenoid Circuit

any thoughts, help, similar issues or suggestions would be appreciated.

 

[Hunter62]

Is your gas cap on tight?

 

[culp71]

Is your gas cap on tight?

tight as always, even replaced it just to try, no diffenerece, as never had CEL come one before due to fuel cap not being tight, SO it is somewhere else
in the system

 

[culp71]

I have since removed and replaced the entire canister , rechecked all line to can, and replaced the fuel cap.
checked neck spout to and from tank as well as the vent (hard) line on the spout
no leaks cracks.
No change.

I can reset the light, with my scanner but as soon as I turn truck off and restart the CEL doesn't turn off after start up like it normally would but remains on, when i scan I get the same two codes over and over :
P0448 Evaporative Emission Control System Vent Control Circuit Shorted
P0449 Evaporative Emission Control System Vent Valve/Solenoid Circuit

any thoughts, help, similar issues or suggestions would be appreciated.

 

[Coastie05]

I have since removed and replaced the entire canister , rechecked all line to can, and replaced the fuel cap.
checked neck spout to and from tank as well as the vent (hard) line on the spout
no leaks cracks.
No change.

I can reset the light, with my scanner but as soon as I turn truck off and restart the CEL doesn't turn off after start up like it normally would but remains on, when i scan I get the same two codes over and over :
P0448 Evaporative Emission Control System Vent Control Circuit Shorted
P0449 Evaporative Emission Control System Vent Valve/Solenoid Circuit

any thoughts, help, similar issues or suggestions would be appreciated.

It may be time for a trip to the dealership. Seems like you’ve already dumped a lot of money and time into this problem. Let us know if this gets resolved!

 

[culp71]

I'll keep on searching and troubleshooting.
I never take any of my things to "the dealership" or anyone else for that matter....no one has respect for anything.

in searching i find some saying P0449 is always electrical not mechanical, other say differently.
with both codes p0448 and p0449 occurring, trying to narrow down if one would set of the other and vise versa.
going to try to find time to start tracing and checking wires next.
I did already replace the connection and plug to the solenoid vent in the canister, but it made no difference.

 

[Cyber Canyon]

Could actually be the evap canister too... 100k and that is a consumable part, they don't work forever.

 

[culp71]

thanks but already replaced that too, per previous post

 

[culp71]

from what I read is the vent solenoid in the canister is always powered 12 v?
but only supplied with a ground to complete the circuit when the pcm tells it too?
is this correct?
what is the best way to trace this wiring system to confirm it is receiving the proper power at the proper time to the canister vent solenoid?