Hi, I'm new to the website. I have a Chevy Silverado Classic 07 4.3 and it has 48,xxx Miles on it. I recently when i was driving i got message on my DIC (tighten gas cap) i stopped and tighten it. later the next day i had the engine light come on (it annoys me to have that engine light )
Well i took it to auto zone and got the code read and got p0455( she said gas cap) so i bought a new one ( put it on ) and then reset the code. Then later the next day i had the engine light come again. I went it took it back and got to rescan and got 3 codes p0442,p0449 & p0455 (im like wahhhah!! ) i dont know what else to do...any had any problems with this?

 

Maybe they gave you the wrong cap. Check these.
OBD-II Trouble Code: P0455 Evaporative Emission Control System Leak Detected (no purge flow or large leak)
OBD-II Trouble Code: P0442 Evaporative Emission Control System Leak Detected (small leak)

 

They programmed the "TIGHTEN FUEL CAP" warning into the DIC because that's the most common reason for an air leak in the EVAP system in these days of self service gas. It's possible that the leak is actually not through the fill cap. If a visual inspection or smell doesn't turn up anything, consider taking it in for service.

 

I already change,the cap but,i,think is,the,vent solenoid is,very,typical with,this,trucks

 

Vent solenoid is a good candidate.
The dealer will charge a lot to replace this part.

DIY

 

yes, VENT SOLENOID under the truck... is attached to charcol canister and located on fuel tank. There is an update for it.