P0449 Code – Evaporative Emission System Vent Valve / Solenoid Circuit

[08Bluesky]

33K miles on car, 1.8L Automatic 2013

Check engine light has been coming on, triggering a P0449 Code, Gas tank is ¾ full. I did a "search" on the site – found (2) references to the code. Found lots of information on the “Generic” code on the Web, mostly pertaining to Chevy Tahoe’s.

Could be the Canister – have to lower the Fuel Tank to get to it,
Could be a shorted wire in the harness,
Could be the Vent Valve,
Could be a circuit fuse.

The Car seems to run fine as usual, only odd thing is that when the code has not been cleared, the Remote start will not fire. Seems the code triggers only upon minutes after start-up. Once it’s running and I clear the code with my OBD2, it does not re-trigger while driving.

Still a tad cold here in the Burgh so I’m thinking it can wait for warmer weather….

Any heads-ups / suggestions as to how to isolate the issue would be greatly appreciated.

Thanks in advance,
Joe

 

[08Bluesky]

Today's observation.....

Upon start-up, code triggers within 15 seconds. I can immediately clear it using the OBD2 and it does NOT come back on while running. (Something to do with open loop / closed loop warm-up / checks??)

 

[JTee2017]

Today's observation.....

Upon start-up, code triggers within 15 seconds. I can immediately clear it using the OBD2 and it does NOT come back on while running. (Something to do with open loop / closed loop warm-up / checks??)

I wouldn't wait too long to further diagnose and repair. When a code is triggered . . almost any code, remote start and maybe remote door unlock will not work. Kind of a "heads up" to take the car in for people who like to put things off and get annoyed and do not like to take there vehicle in to the shop thinking they can wait. ..

Might be a fuel tank wiring harness or associated connector. Check by carefully pulling apart and look for corrosion or broken wires. If corroded, a good washing with Deoxit might help.

Right now, you could also be damaging the catalytic converter or other engine functions it fuel trim is also running rich.

Also,, over filling the gas tank regularly can cause early failure of this kind of part.

Also, I assume you saw these below:

https://www.justanswer.com/chevy/ao8wf-chevrolet-sonic-2014-engine-1-8-code-p0449.html

Chevrolet Sonic Repair Manual: Evaporative Emission Canister Replacement - General - Engine Control - Internal Combustion Powertrain Control - Powertrain

 

[08Bluesky]

Thanks for the responses JTee2017.

So far,
NOT the easy stuff...... “Under hood” Purge Valve nor Fuse #17

 

[Ponchoguy]

Thanks for the responses JTee2017.

So far,
NOT the easy stuff...... “Under hood” Purge Valve nor Fuse #17

Just thinking, would this be covered by some sort of emissions control warranty? Just a thought.....

 

[08Bluesky]

Spring Update -

Dropped the tank far enough to remove the ACDelco Vapor Canister Vent Valve - Bench tested the Valve, same ohms as the original (had hoped to find an open coil) - applied 12VDC - operated fine - much like the original. Replaced it anyway.

Code still comes back

Next....

 

[08Bluesky]

Replaced the Under hood Valve a couple of weeks back because it was easy to get to, relatively cheap and did not seem to hold vacuum – Again, No change in code throwing.

Did another check on “All” uses, not just the ones within the evap circuit.

Bought a new Evap Canister, now awaiting the fuel level to drop to 2 gal or less, makes lowering the tank and Canister removal easier.

 

[08Bluesky]

Took the car to an independent nearby.

They traced the code down to find and open ground - the wiring harness up under the right rear wheel well had been pinched / worn through at a body seam - repaired & re-sealed.

All is well now.

 

[08Bluesky]

Jan 2109 Update

Well the pinched / frayed /worn wires in the wheel well were indeed an issue..... BUT the code returned after a few months. About once a week it showed up – intermittently.

Thinking the repair job was probably done with “Crimp” connectors – I went and cut out what the Indy did and soldered the wires myself…. Didn’t really solve the issue, was still intermittent. Also jumped over the Body connector with hard solder wires… And checked for continuity to the Vent Solenoid connector – Indeed showed a good solid connection. Even located the wires under/along the passenger seat and checked for continuity to the Back Connectors – all looked good. Bought a new connector thinking that I may have weakened it initially when I first tried to remove it from the canister.
As an early test, I placed the New connector in line with the wires I located inside the car…. Connected a Vent Solenoid….. Cleared the code… and expected it to “react” upon start up – But alas it did not.

At that point I FINALLY gave up and made an appointment at the Dealer, took it in…. And Surprise Surprise, They found that the EMC was not “Switching” the Ground signal to the Solenoid… They replaced the Computer “Free” – Under Warranty. 2 months later, the code has not come up.
Much thanks and great respect to Colussy Chevrolet of Bridgeville. And yes, I “Should have” gone directly back to them in the first place.