A system and method for controlling knock in a lean burn internal combustion (IC) engine includes a spark plug having an electrode, an electrical circuit, and a controller. The electrical circuit is configured to provide a first voltage to the electrode and detect an ion current during a thermal-ionization phase of the combustion process, and provide a second voltage to the electrode to create a spark and initiate a combustion process within the combustion chamber. The controller is configured to monitor the ion current for a knock condition that includes at least an incipient knock condition, determine a crank angle of the IC engine where the incipient knock occurs, and adjust timing of the IC engine to operate at a crank angle that does not exceed a threshold level beyond inception of incipient knock.