What causes a GM car to have code 43?
What causes a GM car to have code 43? Typical causes for this code 43 include: 1) BYPASS line is open or grounded 2) EST line is open or grounded 3) PROM or CALPACK not seated properly in the ECM 4) Poor connections between ignition module and ECM 5) Poor routing of EST harness and/or poor quality ignition wires (EMI induced electrical noise) How does DTC 43 work on a GM Truck? The DTC 43 circuit consists of a knock sensor with one wire that goes directly to the PCM. There are two DTC 43 checks performed by the PCM....