codes PO300 PO332 and PO453 help please.

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by ouimetteracing, Jun 23, 2010.

  1. ouimetteracing

    ouimetteracing New Member

    Hi I was looking for some opinions. Just recently a couple of codes and the SES light came up on my 2000 Silverado Z71 with the 5.3. PO453 Evap system pressure high has been on for a little time now and I believe has nothing to do with the other two. I tried the easy fix of replacing the gas cap but the code came right back on after clearing the codes. My main concern right now is the PO300 Multi cylinder misfire and PO 332 Knock sensor circuit low. Both of these last two codes came on at the same time, shortly after I washed down the engine compartment. The truck is misfiring with low power between 1500 and 2000 rpms any higher RPM and it seems to run fine. Where do yall think I should start with this problem? Could it be that the knock sensor got wet and is causing the misfire or the other way around? Also I have tried clearing all the codes but they all come back after running it three times.

    Thanks in advance
    Last edited: Jun 23, 2010
  2. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    I have read on here that the knock sensor can get wet.. I think that was on the 5.7L engine.. But that might be at least a place to start and hopefully someone with a bit more knowledge of the 5.3L will be able to chip in...

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