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replaced knock sensors but still have light

This is a discussion on replaced knock sensors but still have light within the General Help forums, part of the LSx Technical Help Section category; Just got through replacing new knock sensors and harness.Re-connected battery and drove about 7 miles,then service engine soon light comes ...

  1. #1

    replaced knock sensors but still have light

    Just got through replacing new knock sensors and harness.Re-connected battery and drove about 7 miles,then service engine soon light comes back on.Took it back to Auto Zone,scanner said knock sensor again,but this time it said low input 1 & 2.Auto zone cleared it with there scanner but light re-appeared about another few miles.Think I might of got some bad sensors?I purchased them off ebay.Those of you who have done this know how time consuming it is to do this job.Think hard about what I should do?Thanks in advance,Andie.

  2. #2
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    pajeff02's Avatar
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    Black & Blue
    '02 WS.6 / '07 Suburban

    I would shy away from an ebay sensor and install GM sensors. Any chance you pinched the KS wire harness upon installation of the intake?

  3. #3
    None Shall Pass Knight's Avatar
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    99 WS.6 - Modified

    Agree with Jeff's suggestions. Also, are you sure you aren't actually getting a knock? Why did you replace the last set?

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    Veteran 0rion's Avatar
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    06 duramax

    what brand and part number of sensor did you use? I agree with the other guys......it's easy to pinch that harness putting the intake back on. I also think pulling the intake on these cars is a pretty quick and easy job. Once you do it a few times you get much faster at it.

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    Member flybird's Avatar
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    1999 Firebird 3.8 series

    Could be a bad wire to the computer..

    This happend to me. I replaced the KS, knowing I dont have a knock bc its a brand new engine.. Still had the code, so replaced harness.. Still had code. Had to get it rewired all the way to the computer..

  6. #6
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    1998 Pontiac Formula LS6

    I had to deal with this same problem last Dec. For right now the easiest test you could do would be to disconnect the KS harness and verify you have 1000 ohm resistance on both leads. If you have 0 resistance you know you probably pinched the harness somewhere. This test will give you a good idea which direction to go next.

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    Junior Member 9T8WS6's Avatar
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    1998 WS6, ASC BUILD #206

    You probably do not have the same issue I did BUT, my SES light started and would not clear more than a couple miles.
    Computer showed it was a sensor located underneath back near the gas tank.
    We ordered a new sensor and when we started to replace it, we discovered a "RAT" had chewed into the wire and pretty much had it disconected on one side.
    Regardless, I had the new sensor so it was installed, the chewed wire was re-connected and that fixed my SES situation.
    Bottom line, look for wires that may be chewed into or in half.

  8. #8
    expensive tires az gt eater's Avatar
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    Yes, the job of r and r ing the intake seems daunting the first couple of times, but you get quicker at it. I did. Seriously, I would suggest that you pinched the wire harness.

  9. #9
    I bought the sensors off ebay because they were GM.There's a good chance that brand new harness wire got pinched because I was so disgusted after seeing how GM laid that wire ontop of that valley tray to cook,I simply used some thick braided wire and glued back over to protect from heat.There was a pretty big hump left where that wire goes over middle tubing.The motor is running smooth as all get out tho.I'm no mechanic,but I did everything else by book including torqing right.I think all the oil in the intake would give any stock LS1 a knock.

  10. #10
    expensive tires az gt eater's Avatar
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    Catch can next!

  11. #11
    Spaz is My Mentor SMWS6TA's Avatar
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    Navy Blue Metallic
    98 T/A w/a little mods...

    Did you get KS for a 98 or 99< ?


    There is a difference. The >98 KS have been phased out of GM's inventory.

    To use 99< KS you will need a 99< wire harness. Not much about $35.


    The new KS have less potential to give off false reporting of knocking.






    Also I used some masking tape to hold my wire harness in place in the VCT. I learn this important step because I pinched the WH while installing my LS6 intake.


    Last edited by SMWS6TA; 04-22-2012 at 06:04 PM.

  12. #12
    Waiting on the Tree transamtom's Avatar
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    1999 TA A4

    You can also get knock from over torquing the sensors down or using pipe tape on them.
    2010 Camaro SIM 2SS/RS A6
    1999 TA A4 NBM
    12.265 at 110.52mph

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