Diagnostic Aids

Code 43 can be caused by a faulty knock sensor connection at ESC module or ECM. Also, check controller-to-ECM signal line for an open or short to ground.

Fig 1: Code 43, Schematic, Electronic Spark Control

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code 43, Flow Chart, Electronic Spark Control

Courtesy of GENERAL MOTORS CORP.