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Knock Sensor

Discussion in 'General Chevy & GM Tech Questions' started by Tom Evans, Aug 3, 2011.

  1. Tom Evans

    Tom Evans New Member

    My 2002 Suburban with the 5.3 L,flex fuel engine (Z) pulled a P0332 DTC today. The manual says that is the rear knock sensor. To get to the knock sensor, you have to take all of the fuel injection hardware as well as the intake manifold off. Before I do all that work, I want to ask if others have had this problem before and was it typically the sensor? Or was is a bad connection on the top of the sensor? Should I go for exact GM replacement?

    Finally, can I go a few days before I replace the knock sensor? With a malfunctioning knock sensor, will the engine computer permanently place the engine on retarded timing?

    Thanks.
  2. silveradotrailblazer

    silveradotrailblazer New Member ROTM Winner 1000 Posts

    I believe dsfloyd just did his.
  3. Tom Evans

    Tom Evans New Member

    Many thanks to dsfloyd and silveradotrailblazer. When I got into the job, I found out that the rear sensor was very rusty while the front sensor looked like a new one. It looks like water had gotten into the rear sensor well and did the deed over the years. The connector even looked bad for the rear sensor, so I got a new wiring harness as well. The local GM dealer had a number of wiring harnesses in stock which leads me to think that they replace them often. My recommendation is to order two knock sensors, a manifold gasket set and the knock sensor wiring harness (P/N 12601822). Then be sure to use a little RTV when you insall the wiring harness plug.

    One final thing. I couldn't find any information on how to release the connector on the knock sensor. It took a while to finally figure it out. Take a pair of pliers and squeeze the two flat surfaces down low along the sides of the connector and it will pop right off.
  4. ippielb

    ippielb Active Member ROTM Winner 1000 Posts

    Knock sensor replacement on LS1 engines are a pain. They're located UNDER the intake manifold. There is two sensors in two identical indentations on the top of the block. Moisture gets under the intake manifold and settles in those indentations and rusts the knock sensors. By bad design on GM's part.

    To replace the senors remove your intake manifold, and pop off the two rubber grommets that are on the top of the block, there should be one wire coming out of each.

    TifToGif.jpg
    There's going to be a plastic connection that connects to the top of the knock sensor. I would highly recommend purchasing two new pigtails. 90% of the time they break during removal. Easy to replace, cut the wire crimp the two wires together from the pig tail to the stock wire, heat shrink it water tight.

    To remove the knock sensor just take your ratchet and socket and unscrew from the block.
    TifToGif1.jpg
    Then when doing the installation, be sure to use rtv silicone to seal the grommet water tight and air tight.
    TifToGif2.jpg
  5. ippielb

    ippielb Active Member ROTM Winner 1000 Posts

    Here's some real pictures from an 02' 5.3l that had knock sensors replaced.
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    ---------- Post added at 03:25 PM ---------- Previous post was at 03:24 PM ----------

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  6. silveradotrailblazer

    silveradotrailblazer New Member ROTM Winner 1000 Posts

    I would advise anyone doing this to cover/plug the heads intakes immedatly after removing the manifold so nothing gets dropped in the intake port.:grrrrrr: I like to use a shop vac to vaccuum the area around the intake maniflod before removing the manifold and then again when the manifold is removed to help keep dirt from getting into the engine.

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