2007 Colorado p0449 code.

[Yarskram]

Ok I'm at my wits end with this truck. I have replaced the purge valve solenoid, the canister vent valve solenoid, and the gas cap. I am now getting a p0455( Large Evap Leak Detected) code after all of this. The hoses that I can see are in good shape, the electrical connectors are good. Could it be the fuel tank pressure senor? I am really trying not to take it to a shop because I don't have the money. Labor here is $93 an hour and I know I will get hit for at least a $250 bill. I have already spent around $75 for the parts that I installed. What else should I check. Thanking all for any help .

[zora]

if you first had a P0449 and replaced all those parts and now you have P0455, something has been disturbed by the work you did, hose loose, cracked, defective part, etc. The correct thing to do at this point would be a smoke test to find the leak. There is nothing listed in the P0455 pointing to a pressure sensor.
https://www.obd-codes.com/p0455

[Yarskram]

Thanks Zora, I didn't think the pressure sensor would have anything to do with it but that was my last option. In order to do the smoke test what would the procedure be? Do I hook up the tester to the port on the purge valve or the brake booster and let smoke in? Do I run the truck or keep it off? Does the canister valve have to be open or closed? And if so how do I open or close the vent? I do not have a computer that can control the truck. Thnk you again.

[zora]

I'm not sure how you are going to do this yourself. You have to rent or buy the machine, it should come with instructions, typically it attaches to the gas tank fill neck. You also need an air compressor and have to command the valves to open via a scan tool.

[Yarskram]

Yeah that's what I thought about the scan tool. Thank you for your patience and help.