NOTE: Test numbers refer to numbers on diagnostic chart.

If conditions for a Code 43 exist, scan tester will indicate knock signal presence. Knock signal should not exist at idle unless an internal or system problem exists.
Determines if system is currently functioning. Usually, a knock signal can be generated by tapping on exhaust manifold. If knock signal is not generated, try tapping on engine block closer to sensor.
Because Code 43 sets when signal voltage on spark retard line remains low, this test should cause signal on that line to go high. Control module should see 12-volt signal as a "no knock" signal if control module and wiring are okay.
This test will determine if knock signal is being detected on sensor-to-controller line or if ESC module is at fault.
If sensor line is routed too close to secondary ignition wires, ESC module may see induced interference as a knock signal.
This checks ground circuit to module. An open ground will cause voltage on monitored line to constantly remain about 12 volts. This would cause Code 43 functional test to fail.
Contacting sensor-to-controller wire using a test light connected to 12 volts will generate a knock signal to controller. This will determine if ESC controller is operating correctly.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Code 43 - ESC Error (With ESC Module)): Notes