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Check engine light comes on after rain

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Kevin Lester, Apr 2, 2013.

  1. Kevin Lester

    Kevin Lester Junior Member

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    Hi Friends,

    I've got a 2005 Prius. Love it, but the "check engine" light always comes up after it rains (or the snow melts). It goes away a while after things dry out. For instance, yesterday it had rained over night, so the CEL was on in the morning. By the afternoon it was out.

    Anyone know what kind of issue I could have?
     
    #1 Kevin Lester, Apr 2, 2013
  2. Joe 26

    Joe 26 Member

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    Water leaking onto the coils. I'm pretty sure there is a fix for this, perhaps someone else will chime in.
     
    #2 Joe 26, Apr 2, 2013
  3. jdenenberg

    jdenenberg EE Professor

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    There is a known weakness in the rubber seals that prevent water from entering the engine compartment. Easily fixed DIY.

    JeffD
     
    #3 jdenenberg, Apr 2, 2013
  4. Kevin Lester

    Kevin Lester Junior Member

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    So, do I just go pick u replacement seals and install them? What's the DIY solution?
     
    #4 Kevin Lester, Apr 2, 2013
  5. Former Member 68813

    Former Member 68813 Senior Member

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    I didn't know engine compartment was waterproof!
     
    #5 Former Member 68813, Apr 2, 2013
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The DIY solution is to buy a tube of black RTV sealant and use that to caulk the vertical seam that joins the two black plastic cowl pieces that cover the windshield wiper motor assembly. Water can drip down that seam onto the engine valve cover. Once water gets on the valve cover, it can potentially enter a spark plug well if the igniter O-rings are not in perfect condition.

    To determine that this was the cause of the CEL coming on, you might remove the spark igniters and spark plugs and inspect for corrosion. The presence of rust would prove that water had gotten into the spark plug well.
     
    #6 Patrick Wong, Apr 3, 2013
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