[fastlanemech]

I have a Chevy CK 1500 and it has trouble code 43. I switched the knock sensor and now it won't start and I still get a fault code of 43. What could be the problem?

[LATECH]

Code 43 description is "Electronic Spark Timing Malfuntion" it is not just generic as " Knock sensor" .
Although the knock sensor is part of the sytem, it is a code for the system not a specific component. Sub system testing is required and you need the flow chart to do so.
Chances are it needs a ignition module anyhow.
When you replace it , if you do, be sure to use heat transfer grease and not the "token" package of silicate based grease that is supplied in the box with the new part.
Radio shack sells "arctic silver" which is the correct heat transfer grease for the job.
Its a wonder any module lasts as long as they do as most suppliers give that "token " package of grease which is incorrect in its chemical composition.