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Q: evap large leak on 2004 GMC Envoy

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
got code po455 for large evap leak. bought new gas cap and 2 days later same code reappeared. any other possible solutions?
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You should have your fuel line smoked to look for the leak. This is best done at a repair shop because the car can be put on a lift to allow the mechanics to have an easier time finding any parts of the system that leaks. Essentially they will pump smoke into your fuel line and if the smoke escapes from any part of the fuel line, they will know exactly what is leaking. There are a lot of expensive fixes you could try, but if there's other leaks or if what you replace wasn't leaking at all, then it could be a wild goose chase.

I had a leaking valve unit on my truck, replaced it and still had the same code. I was going to replace the fuel neck because it had some minor cracks, but after smoking it I realized it was just a faulty gas cap. Smoking the lines could save you time and money.
I received the code of PO455 on my 2004 envoy. They told me to go home and check the airfilter, it might be dirty and also to check hoses that might have a leak or be loose. i changed the gas cap, the check engine light went off, but came back on later. HELP
Look for a hose that has 34611 on it and see if it isn't split on either end that might just be your 455 code problem
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