How do u know when to replace the knock sensors?

WeaponX

Original poster
Member
Mar 23, 2019
212
Pittston, PA
As I was surfing the web to find a set of new ABS sensors a set of knock sensors passed by so two questions where are they located and when should they be changed? Thanks guys!
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
IIRC, they are located on the side of the block below the intake manifold. Should be changed only if they throw a code. Haven't heard of them failing on this engine.
 
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BrianF

Member
Jul 24, 2013
1,192
West central Sask.
I was thinking this same thing over the past year. Had run into KS issues on my 1993 C1500. Noticed a code and poor performance. After lots of reading, could not find much of anything really for the Atlas. Seems GM made some intelligent engineering choices on this as opposed to the LS truck engines.

Even the old TBI motors had a decently sophisticated system for the KS. Tested its resistance with a reference signal and looked for AC voltage output within a specified range. Anything outside of this and it threw a code.
 

TJBaker57

Member
Aug 16, 2015
2,897
Colorado
Anyone using the Torque App (or other scanners that accept external PIDs?) Here are the knock sensors for the 4.2l. As to what the values should look like I have not a clue,,, If nothing else you can have a look at the values your getting...

20190929_124348.png


 
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