Check Engine only after filling up gas

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by E.D.C., Jul 8, 2017.

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  1. E.D.C.

    E.D.C. New Member

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    Two months ago check engine light came on for small vapor emissions. After checking some things over it seems that the light only turns on after I fill up the gas bladder. If I only put 2-3 gallons in when it's low the light never comes on, was able to go 3 weeks without it. However, as soon as I put 7+ gallons into the bladder the check engine light never fails to turn on within the next 24 hours.

    Anyone hear of this before or have any thoughts?
     
    #1 E.D.C., Jul 8, 2017
  2. JC91006

    JC91006 Senior Member

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    You probably need to tighten your gas cap or get a new one
     
    #2 JC91006, Jul 8, 2017
    E.D.C. likes this.
  3. E.D.C.

    E.D.C. New Member

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    Thanks for the quick reply!
    I'm hoping that's the case, but I put some vaseline around the cap and seemed to help it for a while. My big fear is if it's something else, like a pinhole leak in the gas bladder that only gets exposed when it's stretched tight when full. Check Engine lit up after I filled the gas tank up today, which could be the vaseline is no longer sealing it, or it's related to a full tank as opposed to the half-full I've been filling the tank the past few weeks.
    Possibly crazy, but curious if this is possible before I buy a new gas cap.
     
    #3 E.D.C., Jul 8, 2017
  4. JC91006

    JC91006 Senior Member

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    A gas cap is $15. Great if it works, no big deal if it doesn't.

    Your symptoms are probably related to a bad catalytic converter
     
    #4 JC91006, Jul 9, 2017
  5. bennerzzz

    bennerzzz Junior Member

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    Hey there!

    Not sure if you're still having this problem, but I've been noticing it on my 2002 Prius. It used to only come on when I topped off (only done this twice, not sure why) but today it came on after getting a full tank. Both times the codes read catalytic converter. The first time i took it to a shop and they patched a crack in my converter. The second time it just turned off after driving 3-4 separate occasions.

    Curious to know if you've figured this out!
     
    #5 bennerzzz, Jun 5, 2020
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