so the other day i was driving , normal, and out of the blue i got a check gas cap message. went home and tighten it, it went away. the next day i got a cel but no message so i went to autozone to get the code read and i pulled p0455 and p0497. any idea what to look for as a fix ? about six months away i replaced the evap solenoid. would i need another one? how quickly do they burn out??

 

so random the exact same thing just happened to me sunday
then today on the way to the store it threw the check tire pressure monitor light for like 5 seconds it went away
then threw the check gas cap message and then the CEL light
today it was p0455 yesterday it was p0497

 

I was throwing all of the EVAP codes including P0455

I replaced Vent valve selenoid near the gas tank. No fix

Dealership replaced Evap purge selenoid on the intake manifold. It's a simple fix and you can do it yourself with simple hand tools.

Good luck guys.

Oh and I was getting gas cap message as well as erratic fuel trims and long starts on gas fill up.

 

i am gonna look at mine today see if anything looks loose my friend is just gonna delete the entire code with hp tuners for me on friday until we figure out what to do i am gonna see if i can find instructions for it and order a new one and replace it

 

Jeremey... Ask Nick to get you one from the dealer... Give him 20 dollars for it and I'll meet you and install it. We can do this tomorrow if you want.

 

I wouldn't delete those codes, they are nice to have when the little ****** starts acting up.

 

It could also be a bad gas cap, i've had them intermittently fail.

 

is there a part number for this?? cause i replaced the one by the gas cap already. would this explain the cause of bad gas mileage>

 

mine required a completely new charcoal canister, if you top your cobalt off past the auto stop at the pump you probably filled the canister with gasoline and ruined it. its another possibility to inspect

 

Part # 531 on this drawing:

AP ENGINE ASM-2.0L L4 PART 6 INTAKE MANIFOLD & FUEL RELATED PARTS (LNF/2.0X); AU ENGINE ASM-2.0L L4 PART 6 INTAKE MANIFOLD & FUEL RELATED PARTS (LNF/2.0X); GK ENGINE ASM-2.0L L4 PART 5 INTAKE MANIFOLD & FUEL RELATED PARTS (LHU/2.0V);. Fits: Cobalt, H

PN: 12608378
Solenoid that controls vacuum.

E bay:

GM 12608378 Vapor Canister Purge Valve, New | eBay