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Need a source for a knock sensor for 2003 Malibu Wakesetter

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I have a functional SKU 556015 knock sensor but the threads on it are buggered.  The thread is 1/4" 18 threads per inch, standard, American pipe thread.  Does anyone have a good source to buy a new one, or to fix this one?  I hate to try to force it into the block, and bugger the block. 

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Since automotive, world wide include US has been metric since 1978, I think most of the engine parts are metric thread now. But Bakes sells it with the USA NPT spec, for $80.  SkiDIM, $66.  rontanis.com doesn't sell them. 

Working with Autozone, I got the right one, an SU154, I paid $32 for it.  But once having the part number, I found a significantly cheaper version

on Amazon for others, here, only $14.  


I tried cleaning the thread with a tiny sharp file, plus a Drummel thin abrasive disk, and I got it to start, and go about 2 turn then it kind of locks up using a good female pipe threaded hole in a fitting locked in a vise.  I do not want to force it into the engine, and bugger that side which is still good. 


Thanks for the leads, you guys are always helpful. 

Edited by rm32644
More knowledge, updated/corrected
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I replaced the knock sensor on our 2004 VLX last fall. Monsoon 350. Purchased the new sensor from Auto Zone. Used the number stamped on the original sensor to cross reference the new part. Attempted to take a photo of the number on the new sensor. Looks like 50218015. That may not be the entire number though. I may be able to get a better picture later. 

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Got mine from Summit Racing, online.  Also bought snowmobile oil to get the free shipping.

1 hour ago, rm32644 said:



What do you think would happen if I put a 1/4 18 NPT plug in that threaded block hole,  and left the single wire disconnected? I burn regular gas with 10% alcohol and have never heard detonation.  As I recall, I left the knock sensor wire off accidentally one year, and I got some kind of warning.

You will get code 43 or 44 from your ECM. Comes in above 3200 rpm.


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I was able to take a better picture of the knock sensor. Number stamped on the sensor is 50218015 for certain. A quick Google search did not yield any associated part number. I am certain the sensor was purchased at Auto Zone and is 1/4" 18TPI NPT.  Unfortunately the package for the sensor is at the lake:(

20201023_162848 (002).jpg

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I'm all set, I edited my post above to get the correct Autozone part number, and you can beat the price elsewhere once you start with the part number SU154. 

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Funny, I made a similar post, my threads were gone due to corrosion, I got the stamped numbers off the original sensor and it crossed to a Duralast SU150 and a Standard KS3T.  It was a different number when crossed to a 1999 Chevy 5.7 as someone suggested.

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