EVAP code help!!
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EVAP code help!!
Got an 08 f250 5.4
throwing two codes.
Po455
po457
I read that the po457 points to a bad gas cap but also see if there’s a po455 that means there’s more issues than just the gas cap. I have noticed a drop in my mileage and when I’m getting on the gas for getting up to highway speeds I can hear a swoosh swoosh swoosh sound coming from under the hood. I understand there is some type of pop off/ relief valve under the hood that’s tied into the evap system and it sounds like it could be blowing off. It doesn’t do it all the time just here and there. Wanted to get yalls opinion before I just start throwing parts at it.
throwing two codes.
Po455
po457
I read that the po457 points to a bad gas cap but also see if there’s a po455 that means there’s more issues than just the gas cap. I have noticed a drop in my mileage and when I’m getting on the gas for getting up to highway speeds I can hear a swoosh swoosh swoosh sound coming from under the hood. I understand there is some type of pop off/ relief valve under the hood that’s tied into the evap system and it sounds like it could be blowing off. It doesn’t do it all the time just here and there. Wanted to get yalls opinion before I just start throwing parts at it.
Fleet Owner
Joined: Apr 2008
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Both codes are the result of an air leak which means both or neither can be the result of a leaking gas cap. Doing a smoke test of the EVAP system is the best way to find out what is leaking. The next best thing to do is replace the gas cap, clear the codes, and then see if the codes stay gone.
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