How do you fix a Code 43-ESC on a 1991 Chevy Camaro?

Answer 1

Code 43 is a knock sensor (ESC system fault). If you have a hard 'check engine' light, try this. Disconnect the negative terminal on the battery for a couple of minutes, then reconnect. Start vehicle. If the 'check engine' light comes on within 15-20 seconds or so, chances are either the connection to the sensor is poor, or the sensor is bad (open). Shut off car, then disconnect the connector to the knock sensor. Read the voltage to the connector pigtail (key on engine off). It should be 5 volts. Then ohm check the socket on the sensor itself (to ground); it should be 3.9k (depending on knock sensor used). Run a jumper between the pigtail and the sensor, making sure you have good and solid contact to both. Key on, engine off, the voltage at the connector should now be 2.5 volts. LEAVE THE JUMPER IN PLACE. Disconnect the battery neg terminal again, for a couple of minutes (to clear the code). Reconnect neg battery terminal and with the jumper between the connector and the knock sensor still in place, start the car. If no 'check engine' light within 20-30 seconds, let car continue to run for a few minutes. If still no light, it's the connector that is bad. It could be the pigtail, or the sensor connector itself. I repaired mine without changing the sensor.