Checking for codes came up with code 43 what else can I do to fix it
need to change the esc module were is it on 1993 GMC Sonoma
CHECK THE PLUG OR WIRES THAT GOES TO THE KNOCK SENSOR.
I believe that vehicle has a CPI engine, if so that code indicates a malfunction in the knock sensor system (the ESC - electronic spark control, part of this circut, is not a stand alone module, but an internal part if the vehicle's computer). This is a dual knock sensor vehicle. I am not a big fan of wasting money repalcing parts to fix a check engine light, often times it is a wiring or connection issue, or even a software update. I would suggest testing both knock sensor circuts to pinpoint the cause.