Review on 🚗 Dorman 577-379 Fuel Filler Neck for Compatible Vehicle Models by Michael Cooper

. There were several aftermarket options for this whistle and I've always had good success with Dorman products, but this part caused more trouble than it was worth. A day after replacing the filler neck, I received a service engine. Soon the dash and my Trailblazer were throwing code P0455 (large EVAP system leak). I had trouble putting the gas cap on at first, but it seems to fit well. The dealer recently had a job with the fuel system so I asked him to check the codes not knowing if it was his job or the filler neck. They performed a smoke test and determined the leak was in the gas cap. Four different gas caps were tested on this pen and none fitted properly. This part is no longer made by GM, nor is it available in the US, so I'm waiting for a replacement filler neck from Dorman. Went to the local scrap yard and pulled the filler cap end out of Trailblazer scrap in case the replacement filler had the same problems. it.Edit: Got a replacement part and everything works fine. I noticed that the part I was having trouble with was made in China and the replacement part was made in Taiwan. There were slight differences in the way the brackets were welded to the pipe, as well as the inner plastic part in the filler neck. You can really feel the gas cap sitting snugly on this new part as opposed to the original part I received. I would still check that your gas cap will fit before installing this item.